text:
Variational Autoencoder based Anomaly Detection Variational autoencoder is a probabilistic model which combines bayesian inference with the … ∙ In this paper we apply Variational Autoencoder (VAE) to the problem of anomaly detection in dermatology. The JET baseline scenario is being developed to achieve high fusion Variational autoencoder based anomaly detection using reconstruction probability. 3.2. “Detecting anomalous structures by convolutional sparse models”. Previous works argued that Three common uses of autoencoders are data visualization, data denoising, and data anomaly detection. In the following link, I shared codes to detect and localize anomalies using CAE with only images for training. Our objective is a specific case of β − VAE but from a different derivation. 25 Anomaly detection methods based on autoencoder (AE) appeared. What should I do? Furthermore, we in-troduce attention in the model, by means of a variational self-attention mechanism (VSAM), to improve the performance of the encoding-decoding process. Get the week's most popular data science and artificial intelligence research sent straight to your inbox every Saturday. ∙ A Handy Tool for Anomaly Detection — the PyOD Module. Our objective is a specific case of β − VAE but from a different derivation. Autoencoders usually work with either numerical data or image data. Variational Autoencoder based Anomaly Detection Variational autoencoder is a probabilistic model which combines bayesian inference with the autoenoder framework. Article Google Scholar variational Bayes and variational autoencoders (VAEs), for anomaly detection share. Here I focus on autoencoder. The method based on AE performs anomaly detection through reconstruction di erence [24–27]. ACM, 8--15. Anomaly detection is applied in network intrusion detection, credit card fraud detection, sensor network fault detection, medical diagnosis, and numerous other fields. Figure 8: Anomaly detection with unsupervised deep learning models is an active area of research and is far from solved. Special Lecture on IE, 2, 1-18. Collider, Robust Variational Autoencoder for Tabular Data with Beta Divergence, Autoencoding Features for Aviation Machine Learning Problems, Deep Learning for the Analysis of Disruption Precursors based on Plasma Uncertainty for Anomaly Detection, Peek Inside the Closed World: Evaluating Autoencoder-Based Detection of We propose an anomaly detection method using the reconstruction probability from the variational autoencoder. machine learning (ML) benchmarks and for our application. Variational autoencoders usually work with either image data or text (documents) … Our motivating application is a real world Ser. Evaluate it on the validation set Xvaland visualise the reconstructed error plot (sorted). Find Other Styles Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. framework for anomaly detection in time series data, based on a variational recurrent autoencoder. 06/15/2020 ∙ by Haleh Akrami, et al. 11/03/2020 ∙ by Liya Wang, et al. perf... ∙ ∙ First and foremost, I will introduce one of the models of my ensemble: the classic version of an autoencoder. Wang X, Du Y, Lin S, Cui P, Shen Y, Yang Y (2020) Advae: A self-adversarial variational autoencoder with gaussian anomaly prior knowledgefor anomaly detection. A variational autoencoder is a probabilistic graphical model that combines variational inference with deep learning. In: SNU Data Mining Center, Tech. share. Choose a threshold -like 2 standard deviations from the mean-which determines whether a value is an outlier (anomalies) or not. In addition, many of these derivative technologies, vector quantized variational autoencoder- 2 (VQVAE-2) [ 19, 20 ], anomaly detection with GANs (ADGAN) [ 21 ], and efficient GAN [ 22] have been reported, and anomaly detection in image space has made remarkable progress. ∙ This content was downloaded from IP address 157.55.39.135 on 16/05/2020 at 19:01 In the previous post we did a webinar on how you can perform Automated Vision-Based Inspection and Defect Detection using a 1-class Support Vector Machine (SVM) on image data. Unsupervised_Anomaly_Detection_Brain_MRI/ │ ├── Unsupervised Anomaly Detection Brain-MRI.ipynb - Jupyter notebook to work on Google Colab ├── run.py - execute to run in commandline ├── config.json - holds configuration │ ├── data_loaders/ - Definition … this work, we exploit the deep conditional variational autoencoder (CVAE) and At work, I am tackling anomaly detection by using an ensemble model. memory-based variational autoencoder generation adversarial networks (LSTM-based VAE-GAN) method for time series anomaly detection, which e ectively solves the above problems. The variational autoencoder is a generative model that is able to produce examples that are similar to the ones in the training set, yet that were not present in the original dataset. Previous works argued that training VAE models only with inliers is insufficient and the framework should be significantly modified in order to discriminate the anomalous instances. (image source: Figure 4 of Deep Learning for Anomaly Detection… It learned to represent patterns not existing in this data. - JGuymont/vae-anomaly-detector In “Anomaly Detection with PyOD” I show you how to build a KNN model with PyOD. Knowl-Based Syst 190:105187. VAE is a class of deep generative models which is trained by maximizing the evidence lower bound of data distribution [10]. First and foremost, I will introduce one of the models of my ensemble: the classic version of an autoencoder. share, Building a scalable machine learning system for unsupervised anomaly 10/12/2020 ∙ by Adrian Alan Pol, et al. Because VAE reduces dimensions in a probabilistically sound way, theoretical foundations are … Our method jointly trains the encoder, the generator and the discriminator to take advantage of the mapping ability 0 ∙ 0 ∙ share . Arima based network anomaly detection. Google Scholar; Jinwon An and Sungzoon Cho. ∙ All these methods have their beauty and shortcoming. $\begingroup$ My work is based on Anomaly Detection for Skin Disease Images Using Variational Autoencoder but i have a very small data set (about 5 pictures) that I am replicating to have about 8000 inputs. Unsupervised Anomaly Detection Using Variational Auto-Encoder based Feature Extraction Rong Yao Department of Automation Tsinghua University Beijing, China yaor17@mails.tsinghua.edu.cn [2] Diego Carrera, Giacomo Boracchi, et al. I have a very specific case that I want to work on, am I doing it the wrong way? Anomaly Detection: Autoencoders use the property of a neural network in a special way to accomplish some efficient methods of training networks to learn normal behavior. interest to automatically isolate a time window for a single KPI whose behavior deviates from normal behavior (contextual anomaly – for the definition refer to this post Technical Report. Anomaly detection has a wide range of applications in security area such as network monitoring and smart city/campus construction. 09/06/2020 ∙ by Diogo R. Ferreira, et al. If you’re interested in learning more about anomaly detection, we talk in-depth about the various approaches and applications in … 0 SNU Data Mining Center. ∙ Eng. In: IJCNN. Then, a two-stream Gaussian Mixture Fully Convolutional Variational Autoencoder (GMFC-VAE) is used to learn an anomaly detection model utilizing the normal samples of RGB images and dynamic flows, respectively. Context-encoding Variational Autoencoder for Unsupervised Anomaly Detection @article{Zimmerer2018ContextencodingVA, title={Context-encoding Variational Autoencoder for Unsupervised Anomaly Detection}, author={David Zimmerer and Simon A. Join one of the world's largest A.I. 618 012011 View the article online for updates and enhancements. This paper analyzes and compares a classical and a variational autoencod... The reconstruction probability has a theoretical background making it a more principled and objective anomaly score than the reconstruction error, which is used by autoencoder and principal components based anomaly detection methods. It has become an active research issue of great concern in recent years. Some features of the site may not work correctly. This threshold can by dynamic and depends on the previous errors (moving average, time component). In this section, a self-adversarial Variational Autoencoder (adVAE) for anomaly detection is proposed.To customize plain VAE to fit anomaly detection tasks, we propose the assumption of a Gaussian anomaly prior and introduce the self-adversarial mechanism into traditional VAE. Author: pavithrasv Date created: 2020/05/31 Last modified: 2020/05/31 Description: Detect anomalies in a timeseries using an Autoencoder… Existing anomaly detection solutions also do not provide an easy way to explain or identify attacks in the anomalous traffic. The reason why I selected and implemented this paper, GEE: A Gradient-based Explainable Variational Autoencoder for Network Anomaly Detection, is because it used an autoencoder trained with incomplete and noisy data for an anomaly detection task. このデモでは代わりにVariational Autoencoderを適用した 方法をご紹介します。 VAEは潜在変数に確率分布を使用し、この分布からサンプリングして新しいデータを生成するものです。 Anomaly detection and localization using deep learning(CAE) In this paper we apply Variational Autoencoder (VAE) to the problem of anomaly detection in dermatology. Thus, rather than building an encoder which outputs a single value to describe each latent state attribute, we'll formulate our encoder to describe a probability distribution for each latent attribute. It consists of an encoder, that takes in data $x$ as input and transforms this into a latent representation $z$, and a decoder, that takes a latent representation $z$ and returns a reconstruction $\hat{x}$. Another field of application for autoencoders is anomaly detection. share, The JET baseline scenario is being developed to achieve high fusion Variational autoencoder models make strong assumptions concerning the distribution of latent variables. ∙ The idea to apply it to anomaly detection is very straightforward: 1. Due to the lack of authentication, encryption, and other necessary security protection designs, it has become the main target of malicious attacks under the trend of increasing openness. An encoder learns a vector representation of the input time-series and the decoder uses this representation to reconstruct the time-series. Exploiting the rapid advances in probabilistic inference, in particular variational Bayes and variational autoencoders (VAEs), for anomaly detection (AD) tasks remains an open research question. 3. ∙ Reverse Variational Autoencoder for Visual Attribute Manipulation and Anomaly Detection Lydia Gauerhof∗ Corporate Research, Robert Bosch GmbH lydia.gauerhof@de.bosch.com Nianlong Gu∗ Institute of Neuroinformatics, ETH Zurich niangu@ethz.ch Abstract In this paper, we introduce the ‘Reverse Variational Au- Sci. Exploiting the rapid advances in probabilistic inference, in particular variational Bayes and variational autoencoders (VAEs), for anomaly detection (AD) tasks remains an open research question. 0 Deep neural autoencoders and deep neural variational autoencoders share similarities in architectures, but are used for different purposes. problem: monitoring the trigger system which is a basic component of many This demo highlights how one can use an unsupervised machine learning technique based on an autoencoder to detect an anomaly in sensor data (output pressure of a triplex pump). ∙ In “Anomaly Detection with PyOD” I show you how to build a KNN model with PyOD. The main advantage of a VAE based anomaly detection model over an autoencoder based anomaly detection model is that it provides a probabilistic measure In this study we propose an anomaly detection method using variational autoencoders (VAE) [8]. perf... A comparison of classical and variational autoencoders for anomaly interest to automatically isolate a time window for a single KPI whose behavior deviates from normal behavior (contextual anomaly – for the definition refer to this post Afterwards, we perform anomaly … Image by Arden Dertat via Toward Data Science In this paper, we proposed Donut, an unsupervised anomaly detection algorithm based on VAE. To customize plain VAE to ﬁt anomaly detec- tion tasks, we propose the assumption of a Gaussian anomaly prior and introduce the self-adversarial mech- anism into traditional VAE. Implemented in 7 code libraries. (i) a anomaly level spike and (ii) a sudden drop of body’s centroid height. Tomography. Just for your convenience, I list the algorithms currently supported by PyOD in … “Variational autoencoder based anomaly detection using reconstruction probability”. VAE is a class of deep generative models which is trained by maximizing the evidence lower bound of data distribution [10]. 0 ∙ share, The current practice of manually processing features for high-dimensiona... be significantly modified in order to discriminate the anomalous instances. 2. At work, I am tackling anomaly detection by using an ensemble model. Anomaly detection is a very worthwhile question. {arxiv} cs.LG/1802.03903 Google Scholar; Asrul H Yaacob, Ian KT Tan, Su Fong Chien, and Hon Khi Tan. 09/29/2020 ∙ by Fabrizio Patuzzo, et al. Anomaly Detection With Conditional Variational Autoencoders. Experiments on unsupervised anomaly detection using variational autoencoder. .. Train an auto-encoder on Xtrain with good regularization (preferrably recurrent if Xis a time process). 10/12/2020 ∙ by Adrian Alan Pol, et al. Firstly, based on the Ranking SVM formulation, dynamic flows are generated to represent the motion cue. Industrial control network is a direct interface between information system and physical control process. Semantic Scholar is a free, AI-powered research tool for scientific literature, based at the Allen Institute for AI. We propose an anomaly detection method using the reconstruction probability from the variational autoencoder. ∙ PyOD is a handy tool for anomaly detection. We’ll then train our autoencoder model in an unsupervised fashion. A Handy Tool for Anomaly Detection — the PyOD Module. [1] Jinwon An and Sungzoon Cho. ArXiv e-prints (Feb.. 2018). Face Validation Based Anomaly Detection Using Variational Autoencoder To cite this article: B Zeno et al 2019 IOP Conf. To address these limitations, we develop and present GEE, a framework for detecting and explaining anomalies in network traffic. The reconstruction probability is a probabilistic measure that takes into account the variability of the distribution of variables. Self-adversarial Variational Autoencoder In this section, a self-adversarial Variational Autoencoder (adVAE) for anomaly detection is pro- posed. 3.2. ICCSN'10. ∙ 0 2015. Browse our catalogue of tasks and access state-of-the-art solutions. However, the anomaly is not a simple two-category in reality, so it is difficult to give accurate results through the comparison of similarities. Variational Autoencoders are just one of the tools in our vast portfolio of solutions for anomaly detection. Anomaly Detection. In GEE comprises of two components: (i) Variational Autoencoder (VAE) - an unsupervised deep-learning technique for detecting anomalies, and (ii) a gradient-based fingerprinting technique for explaining anomalies. "Unsupervised Anomaly Detection in Flight Data Using Convolutional Variational Auto-Encoder" Aerospace 7, no. 05/05/2020 ∙ by Seonho Park, et al. Timeseries anomaly detection using an Autoencoder. In Communication Software and Networks, 2010. tabula... VAE based anomaly detection method has a solid theoretic framework and is able to cope with high dimension data, like raw image pixels. [3] Yarin Gal and Zoubin Ghahramani. share, Using variational autoencoders trained on known physics processes, we de... detection, Interpreting Rate-Distortion of Variational Autoencoder and Using Model 2 Variational Autoencoders with Tensorflow Probability Layers - Medium 3 Tensorflow Probability VAE Example 4 Google Colab VAE Interactive Example 5 An, J., & Cho, S. (2015). training VAE models only with inliers is insufficient and the framework should (AD) tasks remains an open research question. 0 The variational autoencoder is implemented in Pytorch. Unsupervised Anomaly Detection via Variational Auto-Encoder for Seasonal KPIs in Web Applications. Instead of the usual optical flow, we adopted popular two-stream network to employ dynamic flows for detecting the motionanomalies. Variational Autoencoder based Anomaly Detection using Reconstruction Probability. 12/11/2019 ∙ by Hang Guo, et al. det... ∙ To the extent of our knowledge, this is the first time that a Variational Autoencoder (VAE) framework has been considered for video anomaly detection. we define an original loss function together with a metric that targets The proposed anomaly detection algorithm separates the normal facial skin temperature from the anomaly facial skin temperature such as “sleepy”, “stressed”, or “unhealthy”. In this paper, we demonstrate the potential of applying Variational Autoencoder (VAE) [10] for anomaly detection in skin disease images. ∙ In this paper, we propose an unsupervised model-based anomaly detection named LVEAD, which assumpts that the anomalies are objects that do not fit perfectly with the model. 2015. My autoencoder anomaly detection accuracy is not good enough. When an outlier data point arrives, the auto-encoder cannot codify it well. To address these limitations, we develop and present GEE, a framework for detecting and explaining anomalies in network traffic. In this paper, we propose a generic, unsupervised and scalable framework for anomaly detection in time series data, based on a variational recurrent autoencoder. Once the autoencoder is trained, I’ll show you how you can use the autoencoder to identify outliers/anomalies in both your training/testing set as well as in new images that are not part of your … Just for your convenience, I list the … Enhancing one-class support vector machines for unsupervised anomaly detection Proceedings of the ACM SIGKDD Workshop on Outlier Detection and Description. Thus, by comparing whether the anomaly score is above a predened threshold, an autoencoder can determine whether the tested data is anomalous. In terms of detection methodology, we propose a variational recurrent autoencoder (VRAE) model to monitor the motion anomaly level, and claim a fall detection when two conditions meet simultaneously, viz. communities, © 2019 Deep AI, Inc. | San Francisco Bay Area | All rights reserved. share, Machine-learning-based anomaly detection (ML-based AD) has been successf... Anomaly detection using Variational Autoencoder (VAE) On shipping inspection for chemical materials, clothing, and food materials, etc, it is necessary to detect defects and impurities in normal products. 8: 115. In the anomaly detection field, only normal data that can be collected easily are often used, since it is difficult to cover the data in the anomaly state. 0 To address these limitations, we develop and present GEE, a framework for detecting and explaining anomalies in network traffic. Exploiting the rapid advances in probabilistic inference, in particular In the The demo also shows how a trained auto-encoder can be deployed on an embedded system through automatic code generation. : Mater. A variational autoencoder (VAE) provides a probabilistic manner for describing an observation in latent space. DDoS to Cloud, Variational Autoencoders for New Physics Mining at the Large Hadron Furthermore, we in- troduce attention in the model, by means of a variational self- attention mechanism (VSAM), to improve the performance of the encoding-decoding process. 11/26/2018 ∙ by Olmo Cerri, et al. In this paper, we demonstrate the potential of applying Variational Autoencoder (VAE) [10] for anomaly detection in skin disease images. particle physics experiments at the CERN Large Hadron Collider (LHC). VAE based anomaly detection method has a solid theoretic framework and is able to cope with high dimension data, like raw image pixels. """. hierarchically structured data AD. GEE comprises of two components: (i)Variational Autoencoder (VAE)- an unsupervised deep-learning technique for detecting anomalies, and (ii)a gradient-based fingerprinting technique for explaining anomalies. share, We propose a robust variational autoencoder with β divergence for The reconstruction probability is a probabilistic measure that takes into account the variability of the distribution of variables. Here I focus on autoencoder. experiments we show the superior performance of this method for classical PyOD is a handy tool for anomaly detection. Get the latest machine learning methods with code. Smart Mining & Manufacturing: Anomaly Detection and localisation using Variational Autoencoder (VAE) Download the Code. A Variational Autoencoder is a type of likelihood-based generative model. From there, we’ll implement an autoencoder architecture that can be used for anomaly detection using Keras and TensorFlow. 2010. Experimental results…, Interpreting Rate-Distortion of Variational Autoencoder and Using Model Uncertainty for Anomaly Detection, Estimation of Dimensions Contributing to Detected Anomalies with Variational Autoencoders, Improved Variational Autoencoder Anomaly Detection in Time Series Data, Inverse-Transform AutoEncoder for Anomaly Detection, MAL DATA MANIFOLD FOR ANOMALY LOCALIZATION, Anomaly Detection with Conditional Variational Autoencoders, Iterative energy-based projection on a normal data manifold for anomaly localization, A Sparse Autoencoder Based Hyperspectral Anomaly Detection Algorihtm Using Residual of Reconstruction Error, Anomaly localization by modeling perceptual features, Continual Learning for Anomaly Detection with Variational Autoencoder, Structured Denoising Autoencoder for Fault Detection and Analysis, Stacked Denoising Autoencoders: Learning Useful Representations in a Deep Network with a Local Denoising Criterion, Stochastic Backpropagation and Approximate Inference in Deep Generative Models, Semi-supervised Learning with Deep Generative Models, Contractive Auto-Encoders: Explicit Invariance During Feature Extraction, Auto-encoder bottleneck features using deep belief networks, Variational Bayesian Inference with Stochastic Search, View 2 excerpts, cites methods and background, 2020 IEEE International Conference on Systems, Man, and Cybernetics (SMC), 2019 18th IEEE International Conference On Machine Learning And Applications (ICMLA), IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium, View 3 excerpts, cites methods and background, ICASSP 2019 - 2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), View 3 excerpts, cites results and methods, View 2 excerpts, references background and methods, View 2 excerpts, references methods and background, 2012 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), By clicking accept or continuing to use the site, you agree to the terms outlined in our.

variational autoencoder anomaly detection 2021


text:
# [OS X TeX] Proportional typewriter?

Thu May 27 21:19:43 EDT 2004

On 27 May 2004, at 21:40, Hans van Maanen wrote:

> I'd like to use Proportional typewriter instead of the regular \texttt
> throughout my document. How do I do this?

Read fntguide.dvi for details. What you want is:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{lettrine}

% The all important line:
\renewcommand{\ttdefault}{lmvtt}

\begin{document}
\lettrine{L}{atin} Modern fonts are enabled with the \texttt{lmodern}
package. Note that they use the T1 encoding so you also need
\end{document}

HTH

W

-----------------------------------------------------
Post: <mailto:MacOSX-TeX at email.esm.psu.edu>

format: plain


text:
# Provide mechanism type ne sono Et3N (cat) sto se H20 Ph Ph1

###### Question:

Provide mechanism

type ne sono Et3N (cat) sto se H20 Ph Ph1

#### Similar Solved Questions

##### 3) The temperature ratio across a moving shock in a 2.5-cm-diameter pipe is 1.204. The static...
3) The temperature ratio across a moving shock in a 2.5-cm-diameter pipe is 1.204. The static pressure and temperature in the pipe in front of the shock are 101.3 kPa and 30°C, respectively. a) Find the shock wave velocity and the air velocity behind the shock, b) The air mass flow rate on both ...
##### How do you calculate (3.2 times 10^-2)( 5 times 10^-3)?
How do you calculate (3.2 times 10^-2)( 5 times 10^-3)?...
##### Would you expect plants growing in the field to exhbit the same type of transpiration rate...
would you expect plants growing in the field to exhbit the same type of transpiration rate as they growing in pots? i need help with this question...
##### What is 4 5/12 * 1 1/3?
What is 4 5/12 * 1 1/3?...
...
##### Given the following class: public class Vehicle { protected String manufacturer; // vehicle manufacturer protected int...
Given the following class: public class Vehicle { protected String manufacturer; // vehicle manufacturer protected int year; // model year protected char fuelType; // G = gas, E = electric, D = diesel, W = wind, U = unknown protected String VIN; // an String to hold the 17 characters of the vehicle&...
##### If 1000 compacted cubic yards in-place of sand/gravel is required, how many loads would be required? The material has an...
If 1000 compacted cubic yards in-place of sand/gravel is required, how many loads would be required? The material has an average percent swell and an average percent shrinkage. Refer to the table in the lecture note to figure out the swell percent and shrinkage percent. Percentage of Swell& Shr...
##### 1.0 A diffuse surface at T = (9400) K. has the spectral, hemispherical emissivity illustrated. Determine...
1.0 A diffuse surface at T = (9400) K. has the spectral, hemispherical emissivity illustrated. Determine the following: E2 0.8 2. = 2 um 12 = 5 um a. the total, hemispherical emissivity is ε = (+0.001) E, () E1 0.4 b. the total emissive power is E = kW/m² (+0.1%) 0 2 5 (um)...


text:
6,342 Answered Questions for the topic Word Problem

13h

#### Math problem: word problem

If I’m driving at 54 mph and it takes 12 minutes and 22 miles to get home. At 2 minutes how many miles have I driven?

#### Physics, work problem

A mover is pushing a 20-kg box up a 30-degree ramp from the ground into a moving truck. He pushes with a constant velocity up the 2.1m ramp. He pushes it without rollers where the coefficient of... more

#### Physics, Energy Problems (confused!)

1) a 2000 kg rollercoaster starts from a height of 55 m and an initrial velocity of 8 m/s. When it reaches the bottom of the hill (height of zero), what is its velocity?2) For the rollercoaster... more

#### Precalculus Word Problem - 3 by 3 or 2 by 3 function

A total of $5000 is invested at 2%, 3% and 4%. The amount invested at 4% equals the total amount invested at 2% and 3%. The total interest for one years is$145. If possible, find the amount... more

#### Precalculus Word Problem - 3 by 3 or 2 by 3 function

A total of $5000 is invested at 2%, 3% and 4%. The amount invested at 4% equals the total amount invested at 2% and 3%. The total interest for one years is$145. If possible, find the amount... more

12d

#### Which of these two women is more likely to be the parent of two girls? Explain.

Professor Robertson and Professor Simpson are both mathematicians. Professor Robertson tells you that she has exactly two children, at least one of whom is a girl. Then Professor Simpson tells you... more

19d

## Still looking for help? Get the right answer, fast.

Get a free answer to a quick problem.
Most questions answered within 4 hours.

#### OR

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.


text:
# zbMATH — the first resource for mathematics

On the volume of a certain polytope. (English) Zbl 0960.05004
Summary: Let $$n\geq 2$$ be an integer and consider the set $$T_n$$ of $$n\times n$$ permutation matrices $$\pi$$ for which $$\pi_{ij}= 0$$ for $$j\geq i+2$$. We study the convex hull $$P_n$$ of $$T_n$$, a polytope of dimension $$\left(\begin{smallmatrix} n\\ 2\end{smallmatrix}\right)$$. We provide evidence for several conjectures involving $$P_n$$, including Conjecture 1: Let $$v_n$$ denote the minimum volume of a simplex with vertices in the affine lattice spanned by $$T_n$$. Then the volume of $$P_n$$ is $$v_n$$ times the product $\prod^{n-2}_{i= 0}{1\over i+1}{2i\choose i}$ of the first $$n-1$$ Catalan numbers. We also give a related result on the Ehrhart polynomial of $$P_n$$.
Editor’s note: After this paper was circulated, Doron Zeilberger [Proof of a conjecture of Chan, Robbins, and Yuen, ETNA, Electron. Trans. Numer. Anal. 9, 147-148, electronic only (1999; Zbl 0941.05006)] proved Conjecture 1, using the authors’ reduction of the original problem to a conjectural combinatorial identity, and sketched the proofs of two others. The problems and methodology presented here gain even further interest thereby.

##### MSC:
 05A15 Exact enumeration problems, generating functions 52B20 Lattice polytopes in convex geometry (including relations with commutative algebra and algebraic geometry) 52A38 Length, area, volume and convex sets (aspects of convex geometry) 52A40 Inequalities and extremum problems involving convexity in convex geometry 05A19 Combinatorial identities, bijective combinatorics
Full Text:
##### References:
 [1] Billera L. J., Formal power series and algebraic combinatorics (New Brunswick, NJ, 1994) pp 1– (1996) [2] DOI: 10.1080/10586458.1999.10504406 · Zbl 0951.05015 [3] DOI: 10.1007/978-1-4612-0801-3_3 [4] Ehrhart E., Polynômes arithmétiques et méthode des polyedres en combinatoire (1977) · Zbl 0337.10019 [5] Hibi T., Algebraic combinatorics on convex polytopes (1992) · Zbl 0772.52008 [6] Postnikov, A. and Stanley, R. P. 1998. [Postnikov and Stanley 1998], Private communication [7] DOI: 10.1016/S0167-5060(08)70717-9 · Zbl 0812.52012 [8] Zeilberger D., ”Proof of a conjecture of Chan, Robbins and Yuen” (1998) · Zbl 0941.05006
This reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. It attempts to reflect the references listed in the original paper as accurately as possible without claiming the completeness or perfect precision of the matching.


text:
New Math Worksheets for Middle School Each Month. Middle School Math Mixed Review: Course 1. Level 1: Easiest (First 2 months of school) Level 2: Next 3 months of school. Level 3: Next 3 months of school. Level 4: Entire course (Final months of school) Middle School Math Mixed Review: Course 2-3.. Here are a couple of quick math puzzles to share at the end of class. Students can take them home to amaze friends and family! The Answer Is 2 Think of a whole number 1 through 10 (We'll use 6) Double it (6×2=12) Add 4 (12+4=16) Divide by 2 (16÷2=8) Subtract the original number (8-6=2) The answer is always 2! The Answer is 18. For many, math is a very intimidating and challenging subject. For others, it is a straightforward exercise in logic. As a teacher of math, you are likely to encounter students of both categories. Whether you are teaching young children or. Place the egg in a cup of water and let it sit for 8 hours. Then remove it and do the same with the corn syrup. After each submersion (vinegar, water, and syrup) have your child observe the changes to the egg. This is an ideal activity to discuss chemistry, osmosis, and how human cells work. The egg is essentially a stand-in for a human cell. Pointing the Way. Move the numbers from the outer frame onto the board so they snake together vertically, horizontally, or diagonally in sequence from 1 to 25. (For example, 2 must touch both 1 and 3.) The catch: You can only move a number in the direction indicated on its home square. Each number fits in its own cell. Interesting Math Problems For Middle School. grammar practice worksheets. number facts games. math is fun sequences. sixth grade math word problems. christmas handwriting worksheets. year 9 math formula sheet. origin math. free year one math worksheets. cool ma5h. math catalog. fourth grade reading comprehension. rocket math reviews. fun ways to learn. Here are a few of the most popular types of Printable Math Brain Teasers: Basic addition and subtraction problems. Multiplication and division problems. Word problems. Logic puzzles. Geometric puzzles. Mazes. Crossword puzzles. Sudoku puzzles.. 1. Math crossword puzzles. Take a crossword, and make it math: that’s the basic concept behind this highly adaptable math challenge. Instead of words, students use numbers to complete the vertical and horizontal strips.. 1 st Grade. In first grade, kids still focus on basic addition and subtraction, but they begin to ramp it up a bit. You can add a bit more difficulty to word problems as well. For example, you may incorporate lengths or coin values into word problems. You want to buy a toy that costs $5.50. You earned$3.. Introduction to the field. To get a job as a middle school math teacher, the steps are basically the same as the steps to follow to become a high school math teacher. You must become certified. To become certified , you will have to pass a state test to get a preliminary license. The state then will give you a license valid for 3 to 5 years. Sep 9, 2015 - Here you will find middle school math problems that can be used in the classroom to challenge your middle school math students. See more ideas about middle school math, math problem solving, math.. For many, math is a very intimidating and challenging subject. For others, it is a straightforward exercise in logic. As a teacher of math, you are likely to encounter students of both categories. Whether you are teaching young children or. Jul 21, 2015 · Well, that would be... wrong. The Answer: 4100. The Explanation: This is just a simple case of your brain getting ahead of itself. You were probs totally on a roll until you got to to the last .... Benton Cmty Middle Senior High School. 10. ... High School. 600 1st St, Van Horne, Iowa | (319) 228-8701. # 10,118 in National Rankings. Overall Score 43.29 /100.. Important! ... power steering line diagram yamaha v star 650 electrical problems. Benton Community High School Alumni in Van Horne, Iowa. Reunite with old classmates, learn about. Here are two bulletin board ideas that can help you set-up the perfect middle-school math classroom. “Circle Math Tree!” is a creative bulletin board idea for learning geometry. Take your board, draw a wide tree on it, and ask children to. The most common methods for solving problems that students may encounter are: Guess and Check; Draw a picture; Work Backward; and. Use an Equation with a variable. The first method on our list of. Our middle school math worksheets cover 6th-8th grade math concepts with simple practice problems. for Teachers for Schools for Working Scholars. Teaching High School Math. The Elementary Math Maniac. A Maths Teacher Writes. He is the most interested in effective technology integration in math classrooms, and developing Subscribe to this blog and get the latest updates. Also in Middle School Teacher Blogs rockstarmathteacher.blogspot. When I was in middle school, there were no math contests. I was lucky enough to have a great If a student comes from the middle of (mathematical) nowhere, with no experiences with math teams The correspondence problem solving serves students to teach themselves for problem solving. Brain teasers, logic puzzles and math riddles give students challenges that encourage problem-solving and logical thinking. They can be used in classroom gamification, and to inspire students to tackle problems they might have previously seen as too difficult. If you want to get your students excited about math class, this post is for you. B. Problem Solving in School Mathematics Curricula C. Classification for Mathematical Problems Ø stimulate students' interest and enthusiasm for problem solving in mathematics, Ø broaden. Once you have passed the trials of basic math, you can move on to the advanced section. This area includes topology, combinatorics, logic, and computational mathematics. Check out the list below for enticing topics to write about: Our specialists will write a custom essay. for $13.00$10.40/page. Learn more. Our middle school math worksheets cover 6th-8th grade math concepts with simple practice problems. for Teachers for Schools for Working Scholars. Problem solving in school, where pressure from externally prescribed compulsory Problem-based Learning (PBL) refers to a range of pedagogies which aim to teach a topic through a progression of problems. Prompting reection is one way to work in the middle ground between the two extremes. The first method on our list of math problem-solving activities for middle school is fairly self-explanatory. In a sense, it involves a bit of reverse-engineering, as the student starts with a. Jul 12, 2021 · Try out a Math Bingo game! Hearing numbers over and over again (and pairing them with correct squares on a bingo card) is the perfect way to reinforce the connection between words and symbols that we use in math problems. Math bingo is exciting and will get students engaged. Have your students make paper clocks and practice telling time!. These are the math concepts that students must understand by the end of the 8th grade. All of these mathematical concepts are used to develop a well rounded base knowledge of mathematical ideas and language as students' progress to higher levels of mathematics. What do students in grade 6 through grade 8 learn in math?. Many of these manipulatives can also be useful in teaching. younger kids as well as high schoolers. Here are our picks for the best math manipulatives for middle school: B est for Fractions: Learning Resources Double-Sided Magnetic Demonstration Rainbow Fraction Circles. Best for Geometry: Learning Resources Folding Geometric Shapes. . B. Problem Solving in School Mathematics Curricula C. Classification for Mathematical Problems Ø stimulate students' interest and enthusiasm for problem solving in mathematics, Ø broaden. Mathematical challenges for families provide interesting math challenges that middle-school students can do at home with their families. Each challenge features: a description of the important math involved ; a note on where the math is used in the real world ; a hint to get started ; complete solutions ; a "Try This" section. Fun and creative math problems to help your students think logically, creatively and mathematically. Brought to you by Noetic Learning "Problem of the Week" program!. and Middle Schools: #2 [HD] Math Olympiads For Elementary And Mathematical Olympiads for Elementary and Middle Schools a not-for-profit 501(c)(3) corporation 2154 ... grades 4-6 and Middle School level problems are for grades 7-8. Math Olympiads |. For a new problem, you will need to begin a new live expert session. You can contact support with I am only able to help with one math problem per session. Which problem would you like to work They may be used by those companies to build a profile of your interests and show you relevant. pathdoc/Shutterstock.com. Problem solving is a great way to strengthen and train the brain for more difficult things as we age. They teach you teamwork, logic, and skill, which are all extremely. Below you can link to hundreds of middle school-level math worksheets throughout our website. These worksheets and printable activities will help students to learn about the absolute value of numbers. Includes identifying values, opposite numbers, ordering, and comparing. Work with basic algebraic expressions, equations, and inequalities.. A great collection of more than 10,000 high school problems with solutions. North Carolina State Mathematics Contests – Problems and solutions from past contests. Pomona College/Univ. of Wisconsin Talent Search – Past tests and solutions; challenging proof problems. Rocket City Math League; Standford Mathematics Tournament. Makedo Windball. Makedo Windball is a simple, yet unique geometry project. Basically, all you do is assemble simple cardboards and turn them into a kind of art form. The main idea behind the. Subscribe Now:http://www.youtube.com/subscription_center?add_user=ehoweducationWatch More:http://www.youtube.com/ehoweducationMath doesn't have to get less e.... Goldbach's conjecture (math.NT) An even integer is a positive integer, which is divisible by $2$. Goldbach's conjecture states that $$\text{"Every even integer greater than 2 can be expressed as the sum of two primes."}$$ For instance, $4= 2 + 2$, $6 = 3 + 3$, $8 = 5 + 3$, $10 = 7 + 3$, $12 = 7 + 5$ and so on. Twin prime conjecture (math.NT). It provides examples and templates of math word problems for 1st to 8th grade classes. There are 120 examples in total. Helping you sort through them to find questions for your students, the resource is categorized by the following skills with some inter-topic overlap: Addition Subtraction Multiplication Division Mixed Operations.
• Below you can link to hundreds of middle school-level math worksheets throughout our website. These worksheets and printable activities will help students to learn about the absolute value of numbers. Includes identifying values, opposite numbers, ordering, and comparing. Work with basic algebraic expressions, equations, and inequalities.
• Favorite challenging math puzzles. In February 2014, I asked my subscribers for their favorite math puzzle. This collection is the result—a list of puzzles chosen by teachers and parents! This page lists the more challenging puzzles. The easier ones are listed on this page. The missing \$1. This is a famous and truly brain-bending riddle!
• These questions are great practice for kids to review some of the things they have been learning in school. Math trivia for kids is also an excellent review if they are out of class right now ... So much time is spent learning how to solve problems; you may never have learned some of these fun facts. ... 168 Amazing Put a Finger Down Questions ...
• HERE'S OUR GROWING COLLECTION Get Google Slide Versions WANT TO SHARE OPEN MIDDLE WITH OTHERS? CHECK OUT THESE FREE WEBINARS TO HELP TEACHERS RETHINK CLASSWORK Elementary Version CHALLENGING MATH PROBLEMS WORTH SOLVING DOWNLOAD OUR FAVORITE PROBLEMS FROM EVERY GRADE LEVEL Get Our Favorite Problems Take The Online Workshop WANT GOOGLE SLIDE ...
• Jun 26, 2017 · The most common methods for solving problems that students may encounter are: Guess and Check; Draw a picture; Work Backward; and. Use an Equation with a variable. The first method on our list of ...


text:
## What is an "alpha answer"?

5

It may seem a bit odd to return a number for the day of the week, so there’s a function to return the day as its name. The DAYNAME function works like DAYOFWEEK or WEEKDAY but returns a string with the name instead, as shown in Example 8-12.

As you can see, an alpha answer returns:

+-----------------------+
| DAYNAME('1964-10-12') |
+-----------------------+
| Monday                |
+-----------------------+
1 row in set (0.00 sec)

Source: Learning PHP & MySQL: Step-by-Step Guide to Creating Database-Driven Web Sites, by Michele E. Davis, Jon A. Phillips

What does an alpha answer mean?

1

In this case, alpha is an abbreviation for alphabetic. The passage is telling us that the DAYNAME function returns an value (answer) consisting only of letters (alpha), rather than a numerical indicator, which is what DAYOFWEEK and WEEKDAY return.

The use of the term alpha answer is not standard English at all. Even in the realm of programming jargon, it's not correct. Though we can determine the meaning from the context, alpha by itself is ambiguous as an abbreviation. It can mean either alphabetic or alphanumeric, both of which are frequently used when talking about strings. Also, answer is the wrong word (even colloquially) for referring to the result yielded by a function. The correct term is return value (often shortened to just value).

In addition to misusing the terms, the sentence containing an alpha answer is semantically wrong. The answer is what's returned, but it's being used as the subject of the sentence when it should be an object. As written, the sentence means the answer is what's doing the returning. This is wrong because the return value is just a value; it doesn't do anything. It's the function that returns something.

Here's how it should be written:

As you can see, the function returns an alphabetic value:

1

"Alpha" is an abbreviation for alphabetic. That sentence could have been written, "As you can see, a string returns."

3I think it's worth making the point that OP's example is not in the least "idiomatic". Personally, I'd go so far as to say it's *ignorant/incorrect*, but that's just me. – FumbleFingers Reinstate Monica – 2014-08-14T21:00:34.730

2Because this is a question about technical programming jargon, I feel compelled to point out that it's wrong to claim that alpha means the same as string. A string may contain any characters, not just alphabetic letters. Indeed, in the example, '1964-10-12' is a string but definitely not alpha. – Esoteric Screen Name – 2014-08-15T04:09:24.157

Since we're going to be pedantic, a string's a superset of alpha characters. The returned valued is a string. There's no claim that they are equivalent. Pointing out how it could also have been written was an attempt to show this is pretty poor documentation without writing a page on the topic - and linking it back to programming terminology. Hell, since we're talking MySQL, varchar is likely even better. – Todd – 2014-08-15T19:08:22.693


text:
# Dos command history

One of the nice things of Linux is the command history – it stores typically the last 1000 commands or so and its saved every time you log out.

DOS does have this through the doskey /history command and you can relatively easily append this to a file:

doskey /history >> %USERPROFILE%\history.txt%

The tricky bit is having this done for you on log out.

Via a Stack Overflow question on bash_history you can get close, using doskey macros which appends to a file on exit.

This only works for the current session though so you need to create a shortcut that runs the command each time with the following Target:
(my apologies if this is missing backslashes, WordPress keeps deleting them!)

%windir%\system32\cmd.exe /K doskey exit=doskey/history$g$g%USERPROFILE%\history.log$texit$1 \$2

Then you just have to remember to type exit each time…

Shortcut target

### Update

I also found three useful commands – but they’re only for your current session. Hat tip to Nifty Computer Tricks:

F3
get last command
F7
current list (use left/right arrow keys to paste to the command line)
F8
auto-complete (type the first few letters)

### Update 2 – Some extra love for the DOS prompt…

If you’ve got this working then I’ve added some extra basics. First you need to install Gow (and I suggest you do it using the Chocolatey package).

Then download my bang.bat / history.bat gist, extract it completely and put the bang.bat and history.bat into the Gow bin directory e.g. C:\Program Files (x86)\Gow\bin. These assume you are saving the history to %USERPROFILE%\history.log.

Then you’ll be able to do commands like history | grep mysql to list all your mysql commands in history.log with their line numbers. Then call bang 123 to execute the specific line of the history.log file.

# OpenVPN connects to VPN but no internet

For those stumbling down a similar path…

tldr; Check that your Windows Firewall is turned off.

## My setup

• OS: Windows 8.1 64-bit laptop
• OpenVPN: OpenVPN 2.3.4 x86_64-w64-mingw32

My OpenVPN has been working for at least 4 months without problem.

First thing to remind yourself is: When you get the VPN working – copy the OpenVPN log of a successful connection and the ipconfig /all to file so that you know what to compare when it breaks next time.

## Notes

• The VPN connection stopped working yesterday 17/10/2014
• Not exactly sure when
• It had been working at my office
• My Windows 7 desktop has a working VPN setup so I can compare the settings
• The OpenVPN gui suggests a connection has been made but no sites can be pinged (see commands below)
• All attempts at inconfig /renew, ipconfig /flushdns nothing worked
• Only differences between Desktop/Laptop I could find in ipconfig /all and OpenVPN logs was that laptop had IPv6 for the WiFi connection turned off and the following extra fail message UDPv4: No Route to Host in the log
• I tried turning IPv6 back on but that didn’t change anything
• Now the UDPv4 message disappeared – but didn’t reappear when I turned off IPv6 again – so that was a red herring
• Possible suggestion from my history when first setting up my VPN (http://www.rickygao.com/troubleshooting-general-failure-in-ping-or-tracert/) was to turn off IPv6 which is what I’d probably done before – but IPv6 is no problem on my Windows 7 desktop
• Pinging even a specific IP address does not work – this confirms its not a DNS issue
• Pinging localhost 127.0.0.1 does work
• Pinging the IP Address of the connected VPN does work
C:\Users\Ian>tracert google.com
Unable to resolve target system name google.com.

Ping request could not find host google.com. Please check the name and try again.

## Solution

Eventually found a solution that was to turn off the windows firewall, which came from this unbuntu forums post which eventually spotted that it was an iptables firewall issue.

## Post mortem

• I thought I’d turned off my firewall and it doesn’t explain why the VPN stopped working
• Best guess is a Windows update changed something in the firewall the caused the problem
• A failed update for Windows Malicious Software Removal Tool for Windows 8, 8.1 and Windows Server 2012, 2012 R2 x64 Edition - October 2014 (KB890830) – this was successfully installed the next day but didn’t help
• A successful Definition Update for Windows Defender - KB2267602 (Definition 1.185.3528.0)

# Google Docs to Markdown to WordPress

I’ve started a fairly standard process of writing a Google Doc when I’m trying to learn something technical that I don’t understand and then if its half useful posting it to WordPress.

I know I could then copy paste the code from there to WordPress – but I’m a fan of writing WordPress posts in Markdown. For one reason, I need to switch all the titles to be one level lower in WordPress than Google Docs and its simpler to do that in Markdown. Also and code I put into Courier font in Google docs gets converted to code in Markdown, but gets lost when copying and pasting.

So I’ve found that there’s a script to export Google Docs. There is an annoying issue in that you have to re-do the steps everytime you want to export a document to Markdown. To get around this, I suggest that you just have one document that you use for converting to Markdown and copy/paste each Google Doc into that. Upon running the script from the Script Editor you get emailed a markdown version of your document.

Then copy & paste the markdown syntax into WordPress.

# Windows Netbeans Composer notes

This is for installing the main packages that Netbeans suggests in the Tools > Options > PHP (tab)

I’m running the following setup currently:

• Windows 8.1 (64-bit)
• Netbeans 8.0.1
• The version of Composer doesn’t really matter

## Global packages

running composer global installs the packages into %APPDATA%\Composer (or ~/.composer/ in Linux)

### PHPUnit

From the installation instructions (https://phpunit.de/manual/current/en/installation.html) do:

composer global require "phpunit/phpunit=4.3.*"

This installs PHPUnit to C:\Users\[username]\AppData\Roaming\Composer\vendor\phpunit and puts the binary to use in Netbeans in C:\Users\[username]\AppData\Roaming\Composer\vendor\bin\phpunit.bat

#### Skeleton Generator

From the installation instructions (https://github.com/sebastianbergmann/phpunit-skeleton-generator) run:

composer global require "phpunit/phpunit-skeleton-generator=*"

### PHP_CodeSniffer

composer global require "squizlabs/php_codesniffer=*"

Then put C:\Users\[username]\AppData\Roaming\Composer\vendor\bin\phpcs.bat into Netbeans Tools > Options > PHP (tab) > Code Analysis (tab) > Code Sniffer section

### Mess Detector

composer global require "phpmd/phpmd=@stable"

Then put C:\Users\[username]\AppData\Roaming\Composer\vendor\bin\phpmd.bat into Netbeans Tools > Options > PHP (tab) > Code Analysis (tab) > Mess Detector section

### apigen

composer global require apigen/apigen:~2.8

Then put C:\Users\[username]\AppData\Roaming\Composer\vendor\bin\apigen.bat into Netbeans

# Installing Node.js on Windows 8

Node comes with an installer, but I hit a couple of bugs that knackered my initial attempts to call either node or npm.

I followed the installation instructions trying to run a command for the first time and got 'node' is not recognized as an internal or external command. For anyone else with the same issue here’s what I stumbled through.

I’m running Windows 8.1 (64-bit) with Node v0.10.32.

1. Run the .msi installer
2. This installs it to C:\Program Files\nodejs

In that directory is node.exe for running node commands and npm.bat for installing node modules.

## Environment variables

The simplest solution for this is just to do a restart, but for thos who don’t want to aka me…

The installer doesn’t seem to install the environment variables properly (at least it didn’t when I was using windows 8).

So although if you edit the Environment variables you will see that C:\Program Files\nodejs in the path, if you go into a command prompt and type echo %PATH% it doesn’t appear.

I’m not sure why – but I had to make a minor modification to the PATH, save it and then put the modification back for the nodejs to show up in the path.

Then you can run either node or npm from anywhere.

Here’s the code just in case something changes:

var http = require('http');
http.createServer(function (req, res) {
res.end('Hello World\n');
}).listen(1337, '127.0.0.1');
console.log('Server running at http://127.0.0.1:1337/');

For some reason even though C:\Program Files\nodejs had been added to the system PATH it wasn’t showing up in my path when running dos commands – it took editing the path and saving it to suddenly show up the nodejs in the path.

Once you’ve got the path set up properly then you just have to create the example.js file and run the following commands from a windows command prompt:

> cd C:\path\to\node\example
> node example.js

## Getting npm working

1. There is a npm.bat command in C:\Program Files\nodejs
2. However there’s a known npm issue that requires that the %APPDATA%\npm directory has been created manually otherwise npm doesn’t work
3. You’ll get an error along the lines Error: ENOENT, stat 'C:\Users\[username]\AppData\Roaming\npm'
4. So you have to create your own %APPDATA%\npm

N.B. For “dummies”, aka me: where ever you run npm install in the windows command prompt it will create a node_modules directory and install the module under there
e.g.

C:\Users\[username]> npm install grunt

will install grunt into C:\Users\[username]\node_modules\grunt not into %APPDATA% or C:\Program Files\nodejs\node_modules

Aside

# rebeccapurple

This site’s background is rebeccapurple, its based on the memory of Eric Meyer’s daughter. I have a daughter of two, so reading his tales of anguish are deeply moving.

# Translating WordPress plugins

If you didn’t write the plugin – how do you translate it? I found lots of information for plugin developers to make their plugins translatable but not for people that just want to translate it.

## Executive summary / tldr;

Install the Codestyling Localization plugin and it will solve your problems.

If you’re feeling brave try the ‘Blank WordPress POT’ and put that in the plugin’s languages directory.

You’ll lose your translations when the plugin gets updated – so keep backups.

## For worker ants who want to know a bit more

1. The plugin must be translatable (It has been internationalized)
1. You can check this by looking through the plugin code
2. Otherwise just carry on and hope that the developer made it translatable
2. Then you need to create a translation file that converts the English words into your language (localize it)
1. A POT (.pot) file is a skeleton file that contains all the words and phrases in the plugin that can be translated
2. A .po file is a .pot file that has had the translated strings in your language added next to each of the translatable phrases
3. When you save a .po file it also generates a .mo file (where as you can read a .po file in notepad you can’t read a .mo file)
3. WordPress plugins rely on .mo files
4. You first need to find the .pot file
1. Typically this will be in the root of the plugin directory
2. Or it will be in a languages directory
3. If you find it, great. Open it in POEdit, do your stuff and save
4. If it hasn’t been created at all …
5. … Then you need to check in the code (look for load_plugin_textdomain in the main plugin file) to see where/if you should create one and create the .pot file yourself

If you don’t know about editing PO files I suggest following the WordPress instructions on using POEdit.

## For developers to ‘internationalize’ their plugins

I recommend using the Blank WordPress POT file that I mention below in the POEdit revisited section.

## Translation fumbling

### POEdit

Initially I tried the POEdit method recommended in WPMU DEV tutorial

However the POT files that I made never worked – they didn’t pick up the translated words. I think it was because of __() and _e() instead of __ and _e.

### makepot.php

• WordPress
and Tom McFarlin talk about using makepot.php but its confusing if you’re not using Linux
• It requires using the wp-plugin as the project name which I assumed that you changed to the name of your plugin but you don’t – it has to stay wp-plugin
so the required command is (for windows):

• cd path\to\tools\i18n
• php makepot.php wp-plugin path\to\plugins\your-plugin-name
• However I got the following error when running it from windows
• Actually this had created the your-plugin-name.pot file in the plugin directory but I just didn t realise because of the error
• If you do want to use makepot.php use grapper’s Github i18n repo which includes all the correct WordPress files rather than the official WordPress subversion directories.

### POEdit revisited

Hidden at the end of the WordPress localization document is the excellent ‘Blank WordPress POT’.

That can be put in the plugin’s languages directory and has instructions for creating the PO files from it:

The pot file include in this folder is ready to use.

1. Double click on it and open it with poedit
2. In poedit goto File → New Catalog from POT file…
3. Select and Open the pot file from the languages folder
4. Enter your name, email address, your language and country (i.e. french fr_FR, german de_DE) to the setting form
5. Click the update button in the main poedit ui.
6. Save the file :
7. For a plugin like filename-xx_XX.po with xx_XX for your language and country.
8. For a theme xx_XX.po
9. That’s it, go to your WordPress blog and see your translation in action. N’joy your blogging!!!

This actually worked first time that I tried it – i.e. it pulled in all the translated strings.

First off you can then save the file as a my-plugin-name.pot file in the languages directory. Then you can add in your translations and save it with the locale xx_XX.po file ending and that should generate the .mo file that you need too.

## Plugins

The simplest route is via the Codestyling Localization plugin.

Once it is installed:

2. Select your locale and it generates an empty .po file
3. Click ‘Rescan’ to populate the .po file
4. Click ‘Edit’ and ‘generate mo file’ to get the .mo file out
Copy your .po files into the wp-content/languages/plugins directory – which might or might not work. If yes, great, if not raise a support query with the plugin developer (be nice and give details).
If developers follow this Geert DeDeckere’s excellent guide on loading WordPress language files the right way then there shouldn’t be a problem with using the wp-content/languages directory.


text:
J Syst Evol ›› 1965, Vol. 10 ›› Issue (1): 57-74.

• Research Articles •

### Revisio Generis Paraphlomis Labiatarum Sinensium

Li Hsi‐Wen

1. (Filii Kunmingensis Instituti Botanici Academiae Sinicae)
• Published:1965-01-17

Abstract: This paper is a part of the outcome of a systematic study of unnamed specimens in the family Labiatae accumulated in recent years. The genus, Microtoena, was established by Prain in 1889. The first species published, M. cymosa Prain should be designated as the type of this genus, but the name was antidated by Clarke’s Plectranthus patchouli, so that the new combination M. patchoulii (C. B. Clarke) C. Y, Wu et Hsuan should now replace M. cymosa as the type. Up to date, Microtoena consists of 20 species and 5 varieties confined to tropical and subtropical regions of southeastern Asia. With regard to the distribution, Yunnan has the greatest concentration of species. 10 species and 4 varieties so far having been found in that province, totalling more than half of the known constituents of this genus accredited to our region. The genus has no representative beyond latitude 32° North. Microtoena patchoulii (C. B. Clarke) C. Y. Wu et Hsuan and Microtoena mollis Lévl. are closely related with Microtoena insuavis (Hance) Prain and were reduced into the latter by many authors, but according to their morphological characters (according to the original descriptions) and distribution they are distinct from that species. Based upon the characters of calyx lobes and the shape of the middle lobe of the lower labium of the corolla, we arrange the species in this paper into 5 series. We are of the opinion that Microtoena? coreana Lévl. is possibly a species of another genus, while Microtoena urticifolia var. subedentata Hand.-Mazz. is perhaps anotherspecies of the genus.


text:
What is the maximum number of subsets we can choose from a set of size 20 such that no two subsets have more than 2 common elemtns.

We have a set which has $$20$$ elements (eg. $$\{1,2,3,...,20\}$$). We want to choose the maximum number of non-empty subsets we can such that none of them has more than 2 common elements. for example $$\{1,2,3,4,5\},\{1,2,3,6,7,8\}$$ Has three common elements. For better clarification, if we wanted to solve this problem for $$4$$ instead of $$20$$ then the best way is to choose all the subsets except the $$\{1,2,3,4\}$$ so the answer in this way is $$15-1 = 14$$.

At first, it is obvious that all 1-element subsets and 2-element subsets can be choosed. So if we name the answer $$A$$ then $$A>C(20,1) + C(20,2)$$. But I am not sure what to do after that. For example I can say we can choose all the 3-element subsets and there will be no problem but we can not choose any other subset if we choose all 3-element subsets. So I don't know whether there is a way to not choose some of 3-element subsets and choose larger-sized subsets such that the answer gets bigger or not.

Note that we don't want to count all the possible ways. We want to find the best way to choose the maximum number of subsets we can that satisfy the condition. And we want to find this maximum number.

I must add that maybe the question can be solved for $$n$$ instead of $$20$$. But I was not sure whether there is a specific answer for the general form of the question. So, I used $$20$$ instead.

Sorry for my English. If the question is not clear, feel free to ask for clarification.

Let $$[20]=\{1,2,3,\dots,20\}$$ and suppose $$S$$ is a family of subsets of $$[20]$$ such that no two elements of $$S$$ have more than two elements in common.

For each set $$X\in S$$ let $$X'=X$$ if $$|X|\le3$$, otherwise let $$X'$$ be some $$3$$-element subset of $$X$$. Let $$S'=\{X':X\in S\}$$. Then $$S'\subseteq\{X\subseteq[20]:|X|\le3\}$$. Since the map $$X\mapsto X'$$ is injective, $$|S|=|S'|\le\binom{20}0+\binom{20}1+\binom{20}2+\binom{20}3=1351$$ so tha maximum is $$1351$$.

Well, $$1351$$ is the answer to your title question where you just wanted "subsets". For your body question, where you threw in "non-empty" for some reason, the answer is of course one less.

P.S. Here is a proof of the fact that the map $$X\to X'$$ defined above is injective. Suppose $$X,Y\in S$$ and $$X'=Y'$$; I have to show that $$X=Y$$.

If $$|X'|=|Y'|\le2$$, then $$X'=X$$ and $$Y'=Y$$, so $$X=Y$$.

If $$|X'|=|Y'|=3$$, then, since $$X'\subseteq X$$ and $$Y'\subseteq Y$$, we have $$X'=Y'\subseteq X\cap Y$$, so $$|X\cap Y|\ge3$$. Since two different elements of $$S$$ can have at most two elements in common, this means that $$X=Y$$.

• Thank you for the answer. But I didn't completely understand why this answer is maximum. How can I say that we cannot omit some of 3-element subsets and add 4-element subsets such that the answer gets larger? Maybe I didn't completely understand why X↦X′ is injective. – amir na Feb 17 at 9:17

You can choose all subsets of size $$3$$ as well, so the lower bound becomes $${20 \choose 1}+{20 \choose 2}+{20 \choose 3}$$.

• You can choose the empty set too, so the maximum is $\binom{20}0+\binom{20}1+\binom{20}2+\binom{20}3$. – bof Feb 16 at 23:50
• @bof: OP said nonempty subsets. I just wonder if we could pick some other size than three and have all the intersections two. – Ross Millikan Feb 17 at 0:00
• I see. OP omitted "nonempty" from the title. – bof Feb 17 at 0:09


text:
## A community for students. Sign up today

Here's the question you clicked on:

## ChristianOrtiz 2 years ago Find the slope of the line that passes through the points (-1, 3) and (3, 5). A. 1/2 B. 1 C.2/5 D.2 When i got the test back i circled B and now that i did it i got A so i want to make sure if its A

• This Question is Closed
1. Yahoo!

$m=\frac{ (y2-y1) }{ (x2-x1) }$

2. hartnn

yes, its A

3. ChristianOrtiz

How did you get A ?

4. hartnn

m= (5-3) / (3-(-1)) = 2/(3+1) = 2/4 = 1/2

5. hartnn

got that ^ ?

6. ChristianOrtiz

Thanks!

7. hartnn

welcome ^_^

#### Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy


text:
Data Migration Query Status

This document introduces the query result, task status, and subtask status of Data Migration (DM).

Query result

» query-status

{
"result": true, # Whether the query is successful.
"msg": "",      # Describes the cause of the unsuccessful query.
{
"taskStatus": "Running",        # The status of the task, including "New", "Running", "Paused", "Stopped", "Finished", and "Error".
"workers": [                    # The list of DM-workers that are used by the task.
"127.0.0.1:8262"
]
},
{
"taskStatus": "Error - Some error occurred in subtask", # A subtask encounters an error and is paused.
"workers": [
"127.0.0.1:8262",
"127.0.0.1:8263"
]
},
{
"taskStatus": "Error - Relay status is Error",  # An error occurs in the Relay processing unit corresponding to a subtask that is in the Sync phase.
"workers": [
"127.0.0.1:8263",
"127.0.0.1:8264"
]
}
]
}

For detailed descriptions of taskStatus under the tasks section, refer to Task status.

It is recommended that you use query-status by the following steps:

1. Use query-status to check whether each on-going task is in the normal state.
2. If any error occurs in a task, use the query-status <taskName> command to see detailed error information. <taskName> in this command indicates the name of the task that encounters the error.

The status of a DM migration task depends on the status of each subtask assigned to DM-worker. For detailed descriptions of subtask status, see Subtask status. The table below shows how the subtask status is related to task status.

One subtask is in the paused state and error information is returned. Error - Some error occurred in subtask
One subtask in the Sync phase is in the Running state but its Relay processing unit is not running (in the Error/Paused/Stopped state). Error - Relay status is Error/Paused/Stopped
One subtask is in the Paused state and no error information is returned. Paused
All subtasks are in the New state. New
All subtasks are in the Finished state. Finished
All subtasks are in the Stopped state. Stopped
Other situations Running

Detailed query result

» query-status test

» query-status
{
"result": true,     # Whether the query is successful.
"msg": "",          # Describes the cause for the unsuccessful query.
"workers": [                            # DM-worker list.
{
"result": true,
"worker": "172.17.0.2:8262",   # The host:port information of the DM-worker.
"msg": "",
"subTaskStatus": [              # The information of all the subtasks of the DM-worker.
{
"name": "test",         # The name of the subtask.
"stage": "Running",     # The running status of the subtask, including "New", "Running", "Paused", "Stopped", and "Finished".
"unit": "Sync",         # The processing unit of DM, including "Check", "Dump", "Load", and "Sync".
"result": null,         # Displays the error information if a subtask fails.
"unresolvedDDLLockID": "test-test.t_target",    # The sharding DDL lock ID, used for manually handling the sharding DDL
# lock in the abnormal condition.
"sync": {                   # The replication information of the Sync processing unit. This information is about the
# same component with the current processing unit.
"totalEvents": "12",    # The total number of binlog events that are replicated in this subtask.
"totalTps": "1",        # The number of binlog events that are replicated in this subtask per second.
"recentTps": "1",       # The number of binlog events that are replicated in this subtask in the last one second.
"masterBinlog": "(bin.000001, 3234)",                               # The binlog position in the upstream database.
"masterBinlogGtid": "c0149e17-dff1-11e8-b6a8-0242ac110004:1-14",    # The GTID information in the upstream database.
"syncerBinlog": "(bin.000001, 2525)",                               # The position of the binlog that has been replicated
# in the Sync processing unit.
"syncerBinlogGtid": "",                                             # It is always empty because Sync does not use GTID to
# replicate data.
"blockingDDLs": [       # The DDL list that is blocked currently. It is not empty only when all the upstream tables of this
# DM-worker are in the "synced" status. In this case, it indicates the sharding DDL statements to be executed or that are skipped.
"USE test; ALTER TABLE test.t_target DROP COLUMN age;"
],
"unresolvedGroups": [   # The sharding group that is not resolved.
{
"target": "test.t_target",                  # The downstream database table to be replicated.
"DDLs": [
"USE test; ALTER TABLE test.t_target DROP COLUMN age;"
],
"firstPos": "(bin|000001.000001, 3130)",        # The starting position of the sharding DDL statement.
"synced": [                                     # The upstream sharded table whose executed sharding DDL statement has been read by the Sync unit.
"test.t2"
"test.t3"
"test.t1"
],
"unsynced": [                                   # The upstream table that has not executed this sharding DDL
# statement. If any upstream tables have not finished replication,
# blockingDDLs is empty.
]
}
],
"synced": false         # Whether the incremental replication catches up with the upstream and has the same binlog position as that in the
# upstream. The save point is not refreshed in real time in the Sync background, so "false" of "synced"
# does not always mean a replication delay exits.
}
}
],
"relayStatus": {    # The replication status of the relay log.
"masterBinlog": "(bin.000001, 3234)",                               # The binlog position of the upstream database.
"masterBinlogGtid": "c0149e17-dff1-11e8-b6a8-0242ac110004:1-14",    # The binlog GTID information of the upstream database.
"relaySubDir": "c0149e17-dff1-11e8-b6a8-0242ac110004.000001",       # The currently used subdirectory of the relay log.
"relayBinlog": "(bin.000001, 3234)",                                # The position of the binlog that has been pulled to the local storage.
"relayBinlogGtid": "c0149e17-dff1-11e8-b6a8-0242ac110004:1-14",     # The GTID information of the binlog that has been pulled to the local
# storage.
"relayCatchUpMaster": true,     # Whether the progress of replicating the relay log in the local storage has been the same as that in
# the upstream.
"stage": "Running",             # The status of the Sync processing unit of the relay log.
"result": null
},
"sourceID": "172.17.0.2:3306"        # ID of the upstream instance or replication group
},
{
"result": true,
"worker": "172.17.0.3:8262",
"msg": "",
{
"name": "test",
"stage": "Running",
"result": null,
"unresolvedDDLLockID": "",
"load": {                   # The replication information of the Load processing unit.
"finishedBytes": "115", # The number of bytes that have been loaded.
"totalBytes": "452",    # The total number of bytes that need to be loaded.
}
}
],
"relayStatus": {
"masterBinlog": "(bin.000001, 28507)",
"masterBinlogGtid": "c0149e17-dff1-11e8-b6a8-0242ac110004:1-96",
"relaySubDir": "c0149e17-dff1-11e8-b6a8-0242ac110004.000001",
"relayBinlog": "(bin.000001, 28507)",
"relayBinlogGtid": "c0149e17-dff1-11e8-b6a8-0242ac110004:1-96",
"relayCatchUpMaster": true,
"stage": "Running",
"result": null
},
"sourceID": "172.17.0.3:3306"
},
{
"result": true,
"worker": "172.17.0.6:8262",
"msg": "",
{
"name": "test",
"stage": "Paused",
"result": {                 # The error example.
"isCanceled": false,
"errors": [
{
"Type": "ExecSQL",
}
],
"detail": null
},
"unresolvedDDLLockID": "",
"finishedBytes": "0",
"totalBytes": "156",
"progress": "0.00 %"
}
}
],
"relayStatus": {
"masterBinlog": "(bin.000001, 1691)",
"masterBinlogGtid": "97b5142f-e19c-11e8-808c-0242ac110005:1-9",
"relaySubDir": "97b5142f-e19c-11e8-808c-0242ac110005.000001",
"relayBinlog": "(bin.000001, 1691)",
"relayBinlogGtid": "97b5142f-e19c-11e8-808c-0242ac110005:1-9",
"relayCatchUpMaster": true,
"stage": "Running",
"result": null,
"sourceID": "172.17.0.6:3306"
}
}
]
}

For the status description and status switch relationship of “stage” of “subTaskStatus” of “workers”, see Subtask status.

For operation details of “unresolvedDDLLockID” of “subTaskStatus” of “workers”, see Handle Sharding DDL Locks Manually.

Status description

• New:

• The initial status.
• If the subtask does not encounter an error, it is switched to Running; otherwise it is switched to Paused.
• Running: The normal running status.

• Paused:

• The paused status.
• If the subtask encounters an error, it is switched to Paused.
• If you run pause-task when the subtask is in the Running status, the task is switched to Paused.
• When the subtask is in this status, you can run the resume-task command to resume the task.
• Stopped:

• The stopped status.
• If you run stop-task when the subtask is in the Running or Paused status, the task is switched to Stopped.
• When the subtask is in this status, you cannot use resume-task to resume the task.
• Finished:

• Only when the full replication subtask is finished normally, the task is switched to this status.

Status switch diagram

                                         error occurs
New --------------------------------|
|                                  |


text:
# Can we make new definitions for InputForm in packages?

Those who don't have/prefer the front end of Mathematica will either use a plain ASCII editor to write a script in an .m file or just use Mathematica directly from a command-line terminal. In either case, everything must be supplied in InputForm.

When working with a Mathematica package, commonly used symbols/functions might be excessively verbose in InputForm, and certain shortcuts/aliases would be greatly desired. Examples of built-in InputForm shortcuts are the infix operators + (Plus), - (Minus), ... and . (Dot).

Two questions that arise as a package developer:

1. Can I make definitions to InputForm? That is, can I modify how input supplied as InputForm gets parsed into FullForm?

2. (152744)

Example 1

<...> should correspond to AngleBracket. That is, <a,b,c> should correspond to AngleBracket[a,b,c].

Example 2

Remap character . to package function myDot:

1. a.b.c should be no longer be parsed in InputForm as Dot[a,b,c]
2. It should be parsed myDot[a,b,c].

(n.b. the solution for the analogous question in StandardForm assuming a front end is here.)

• It would be helpful to provide an example of a shortcut you would like to have. – Carl Woll Jul 31 '17 at 17:06
• @CarlWoll Good point, I've added a couple examples. – QuantumDot Jul 31 '17 at 17:17

Consider something as simple as your dot example. Presumably you want 2.3 to be the real number 2.3, not myDot[2,3]. How would you express that? In the box world you can redefine RowBox[{_,",",_}], but that's only because the FE has done the hardw ork for you of figuring out that 2.3 is boxed as "2.3", not as a RowBox[{"2",".","3"}]. The < > example is worse (and would be hard to do in an FE as well), because you're changing < and > from seaparate, binary operators to a matched pair.
The best I can recommend is to find an operator without built in meaning, like say \[CenterDot], and attach definitions to the corresponding symbol. If you have a keyboard which has a center dot key (or shortcut) that's convinient for you, you can just use that. Otherwise, you'd have to type in \[CenterDot] each time, at which point you may as well be typing myDot[...].
• I was afraid this would be the case. I guess the next-best thing to do is to create additional definition of functions with shorter names that point to the longer named functions in the package. Unfortunately, such things wouldn't work in pattern matching if HoldPattern is used. – QuantumDot Jul 31 '17 at 22:01


text:
#### Tang

A projection or lug used to hold or drive an attached part. Tang on a file to hold the handle.


text:
# Potential due to non-uniformly charged disk

1. Feb 26, 2016

### mawgs

1. The problem statement, all variables and given/known data

2. Equations
v=q/4πrε

3. Attempt at solution
Can I find the total charge by integrating the charge density equation from 0 to 2π and then plug that into the above equation?

2. Feb 26, 2016

### TSny

No, you can't treat the entire disk as a single point charge.

Roll up your sleeves and integrate.

[EDIT: Sorry. From the thread title, I was thinking of a disk, not a ring. Yes you can treat the ring as a single point charge because all the charge elements are at the same distance from the point on the axis. (But you still need to integrate to find the charge.) Make sure you use the correct value for r in v=q/4πrε.]

Last edited: Feb 26, 2016


text:
# Trace properties of the gauge potential in non-Abelian gauge theory

I want to proof equation 69.18 in Srednicki's book "Quantum field theory", which reads: $$$$A_\mu^a(x)=2\text{Tr}[A_\mu(x)T^a].\tag{69.18}$$$$ $$A_\mu(x)$$ is the non-Abelian gauge field and $$T^a$$ are the generator matrices, which can be used to expand $$A_\mu(x)$$ as $$$$A_\mu(x)=A_\mu^a(x)T^a.\tag{69.17}$$$$

Srednicki uses the normalisation $$$$\text{Tr}[T^aT^b]=\frac{1}{2}\delta^{ab}.\tag{69.8}$$$$

A simple proof seems to be: \begin{aligned} 2\text{Tr}[A_\mu(x)T^a]&=2\text{Tr}[A_\mu^b(x)T^bT^a] \\ &=2\text{Tr}[T^bT^a] A_\mu^b(x) \\ &=2 \left( \frac{1}{2}\delta^{ab} \right) A_\mu^b(x) \\ &=A_\mu^a(x) . \end{aligned} If it is correct, then why is the following equality true? (second equality above)

$$$$2\text{Tr}[A_\mu^b(x)T^bT^a]=2\text{Tr}[T^bT^a] A_\mu^b(x).$$$$ The the elements of the gaugefield are matrices, so it is not obvious why it should be true. Note that the elements of the gaugefield are traceless and hermitian, maybe this plays a role in the resolution to my question.

$$\mathsf A^\mu = A^\mu_a \mathsf T^a$$ is a matrix but $$A^a_\mu$$ is not.


text:
February 12, 2016

# Polymorphism in C

Polymorphic behavior is an incredibly useful construct in software systems. There are generally two ways by which a program can be constructed to exhibit polymorphic behavior. Namely, through composition or inheritance. Polymorphism via composition relies on (1) well-defined and narrow interfaces and (2) other objects or types containing references to things that implement those interfaces. To give a modern example, consider the following Go program.

We have a generic animal interface and then two structs that implement this interface: dog and cat. Each animal has a description which is able to produce a simple description of the animal. When animals are asked to identify themselves they invoke ask their specific description implementation for a description. This is the fundamental idea behind polymorphism behind composition. Since the description fields embedded in the animal structs implements some well-known interface (in this case, just the description one), the specific instance of that field determines the behavior of the animal at runtime. Thus, we say that polymorphic behavior is achieved by delegating to the implementation of an object.

Inheritance, on the other hand, achieves polymorphic behavior through the interface of a class. Or, put another way, composition allows reuse at the object level whereas inheritance allows for reuse at the class level. For example, if a class called Child inherits from a class called Parent then it must be true that a Child instance can be substituted in any place where an instance of type Parent is needed. This is the basic idea behind the Liskov Substitution Principle [1] and is the L in the famed SOLID principles for OO programming.

Most pragmatic programmers recognize that code re-use is more easily achieved through composition than inheritance since polymorphic behavior is not bound to compile-time types but rather run-time object instances. Many design patterns such as the Strategy pattern [2] use composition (object delegation) for polymorphic behavior. This is regarded as the Composite Reuse Principle in the literature [3].

Even still, inheritance has its place for a reason. When an object truly does exemplify the is-a relationship instead of a has-a relationship, inheritance is perfectly plausible. For example, an array list is most certainly a specific type of list, and so making an array list implementation inherit from a generic list implementation (or implement a list interface) is quite acceptable.

This leads me to the main topic of this post. Since I spend the majority of my time programming in C, which is not an object-oriented language, I often find myself yearning for the benefits of inheritance. To that end, I will discuss one way of implementing polymorphism in C via C++-like inheritance.

# Polymorphic Shapes

To show how we might implement polymorphic behavior via inheritance we will implement a general Shape hierarchy. For now, shapes will only have the ability to compute their area. We will implement concrete Square and Circle shapes that will be “instances of” the Shape “class.” Before showing the code, I’ll first describe the general design. The Shape base will be responsible for two things: (1) storing a table of function pointers that point to the implementations of specific (concrete) functions (e.g., Circle’s Area function) and (2) invoking the correct concrete function with the appropriate concrete instance. This is done by storing a function table and pointer to the concrete type in a Shape instance. This code is shown below.

Shapes are created with a pointer to the instance and a specific function table (ShapeInterface). In the shape_Area function, we simply call the Area function in the function table and pass in the instance provided during construction.

To implement concrete Shape types we need to write functions that adhere to the interface specified in the shape interface. Specifically, we need to implement the Area function, which takes as input a pointer to something and returns a double. The following code shows how we might do this for a Square.

And now for a Circle.

That’s it. We have the pieces necessary to create concrete Shape types and then instantiate general Shapes from them. This allows us to pass around Circles and Squares wherever Shapes are needed, thereby abiding by Liskov’s principle. The code below shows how we might create a Circle and Square instance, “cast” them to general Shape instances, and then compute their area through the shape_Area function.

# Differences from C++

As an object-oriented language, C++ also provides polymorphism through inheritance. And it does so using a similar technique to what I described above for shapes. Specifically, it uses what’s called a virtual function table (vtable) to point to the appropriate implementations of functions [4]. In C++, the compiler is responsible for configuring the vtable for a class hierarchy. It inserts a reserved field called __vptr in the base class of a hierarchy. This field points to the vtable for an object belonging to that hierarchy. Specifically, when an object from this hierarchy is created, the __vptr field is initialized to point to the vtable of the object’s class (not the base class… unless the object is an instance of the base class). The fields of this vtable instance point to implementations of each function for the respective class. For example, using our shape example again, if a Circle object was created then the vtable Area function would point to the Circle’s implementation of the Area function rather than the Shape’s implementation.

Whenever a virtual function is invoked, the resolution procedure works as follows:

1. Retrieve the vtable pointed to by __vptr.
2. Retrieve the function pointer for the association function.
3. Invoke the function via its pointer.

In our Shape example, the vtable configuration would look like the following.

The C implementation I provided does not do any of this automatic table wiring for us. We must do this at compile time. This can be seen as a benefit since we can rely on the compiler to catch function table wiring problems for us. However, it is quite cumbersome to define new “subclasses.” You have to make the decision about whether it’s important yourself.

You can view an example of this code in the Gist below.


text:
# Cfd Definition and 35 Discussions

Computational fluid dynamics (CFD) are used to understand complex thermal flow regimes in power plants. The thermal power plant may be divided into different subsectors and the CFD analysis applied to critical equipment/components - mainly different types of heat exchangers - which are of crucial significance for efficient and trouble free long-term operation of the plant.

View More On Wikipedia.org
1. ### I Flow rate calculation of coating application

Dear all, I'm currently working on a basic coating application and I'm struggling to get the flow rate stable. I'm trying to figure out how to calculate the theoretical flow rate in the application. The coating is stored in a pressure tank, which we put on an overpressure of 15psi. From the...
2. ### Modelling of two phase flow in packed bed (continued)

Previous post linked here, where a model for the two phase flow of air through a packed bed was developed: https://www.physicsforums.com/threads/modelling-of-two-phase-flow-in-packed-bed-using-conservation-equations.1008754/ The first few comments on this new thread will be copies of the...
3. ### Modelling of two phase flow in packed bed using conservation equations

Previously, I have seen the derivation of the energy conservation equations for simulation of single phase flow in a porous media (a packed bed). These are the energy equations for the solid and fluid respectively: I understand the derivation, however, these equations will only work when the...
4. ### Typical surface roughness heights for aircraft surfaces

Hello! I am investigating some preliminary aerodynamics on a regional turboprop and for the drag model the surface roughness height of the airplane is required as an input. For this i do not have any data. In which range are the typical values for modern aircraft surfaces? Thanks a lot!
5. ### Counterfactual Definiteness and MWI in Wiki

Summary: Counterfactual Definitiveness and Many World's Interpretation Sorry for all these threads, my noetic fluids and bursting. Wiki states the following: In quantum mechanics, counterfactual definiteness (CFD) is the ability to speak "meaningfully" of the definiteness of the results of...
6. ### Ridiculously low drag coefficient from OpenFOAM CFD

(New thread following up to a conversation in another thread). I'm using SimFlow 3.1 with OpenFOAM 5 on Linux to try to evaluate the drag coefficient of a water rocket body, constructed from a 2-liter Coke bottle with a conical nose, traveling through air at 77 m/s. This should be a simple...
7. ### Navier-Stokes Equations - Numberphile

Tom Crawford (sporting a Navier-Stokes tattoo) talks about the famed equations - subject of a \$1m Millennium Prize.

18. ### Courses Is CFD fluid mechanics + computer science?

I'm having fluid dynamics classes right now and I'm enjoying it very much (much more than my solid mechanics classes, by the way). Also, I do like programming and computer science, and CFD looks like a very interesting field. I'm developing a real interest for it. One question for those who are...
19. ### Engineering Opening a CFD consulting firm?

I've been thinking about entrepreneurship in the engineering field. Unlike other fields like computer science, where small companies with small investments often end up becoming huge business, engineering is usually a very expensive thing. So consulting is a way for those who don't want to work...
20. ### CFD turbulent fluid, discussion about pressure gradient

I simulated an incompressible turbulent flow across a tube. I managed to solve it using OpenFoam and the results seem to be right. However, I noted some vacuum pressure after the sudden expansion but can't figure out why the pressure decreases and then increases again. According to Bernoulli's...
21. ### A How to solve (or close) the incompressible Navier-Stokes flow eqs for a compressible fluid?

I did a lot of googling but could not find a satisfying answer to my question, hence a post here. Question: How to solve (or close) the isothermal incompressible Navier-Stokes equations for an isothermal compressible fluid? Situation: We have a compressible fluid, for example a gas. The flow...
22. ### A FEM for solving PDEs

Hi, my background is in mathematics, and theoretical physics. I am new to the realm of solving PDEs using Finite element methods, does anyone know of any good introductory level textbooks for course notes? I had a poke around online and couldn't find anything overly useful. Also I am...
23. ### Guidance or tutorial of applying pseudo-material method

Hi, I'm working on a project of coupled simulation involving MCNP and Fluent, and having trouble with how to apply the pseudo-material method in cross section handling. Is there any related material or tutorial? Or, does anyone know the procedure of applying the method and what kind of files the...
24. ### CFD of pressure reducing regulator - Please help

I'm looking for an example of CFD analysis on a pressure reducing regulator. I think may be fairly complicated because the main valve position is not fixed but rather controlled by the pressure differential acting across the valve, the main valve spring, and the load spring minus the pressure...
25. ### Python Doublet + Uniform Flow // Streamfunction Polar Plot Help

Hello, Python,CFD and PF newbie here. I am using Spyder (Python 3.5) and I managed to plot my streamfunction in cartesian coordinates. I tried transforming and plotting in polar coordinates but I am not sure that what i have done is correct. I am not even sure what the plot should look like :/...
26. ### Polyflow terms

What is the "plane of symmetry", "zero velocity wall" and "free surface" terms which I have seen in Polyflow? It says in Vnormal=Fs=0 for plane of symmetry and Vnormal= Vs= 0 for zero velocity Wall. Now I get when Vs=Vn=0 it means that the wall isn't moving and it's in a static state but didnt...
27. ### Fluid solid interaction boundary condition problem

I have come across the paper attached in which a 1D fluid piston is modeled. I have question on the boundary conditions (BCs) of the system. Essentially, the problem consists of a fluid chamber in contact with a spring (a mass -spring system). ALE is used to move the mesh. I am not certain...
28. ### Relation between energy conservation and numerical stability

Hi, Consider the conservation laws for an isothermal linear incompressible flow governed by the mass and momentum equation. The kinetic energy equation is then solved to see if energy conserved. Can anyone tell me if once it is shown energy is conserved, it implies that convergence is obtained...
29. ### CFD Thermodynamics flow in Angular momentum system

Angular momentum is conserved in a closed system. Is thermal isolation required too? An example special case in mind is a closed cavity high speed rotation. It contains high pressure gas and the thermal flow is driving convection currents creating turbulence and or a heat pumping loop...
30. ### ANSYS Mesher face views

Homework Statement I have a part in my ANSYS Mesher that I am attempting to mesh Homework Equations I need to view the interior of my part as seen in the photo. However, each time I try to view my mesh this way, I get the view seen in the second image. I need to fix this issue so that I can...
31. ### Turbulence viscocity

whats turbulent viscocity?How it different from viscocity?Also i read that viscocity is fluid property.So has flow condition like laminar or turbulent has any effect on viscocity?
32. ### Engineering Nuclear Engineering vs Mechanical Engineering

I have a bachelor degree in Mechanical Engineering and I am interested in CFD. I have an admit offer for MS in Nuclear Engineering at UIUC with RA and MS in Mechanical Engineering at Stanford without any assistantship. Which one is a better option to choose considering the fact that I am not a...
33. ### Comparison between CFD results and experimental data

Hi everybody, my question is not properly about CFD but mainly about Fluid Dynamics itself. I have performed a RANS simulation of a round jet of methane and air and now I'd like to compare those results to some experiments. Unfortunately there aren't papers about experimental data for...
34. ### Can applied physicists be CFD analysts

I am about to graduate with an aerospace engineering degree. I am planning to go into grad school for Applied physics(probably plasma physics), which I find very interesting. But the main reason I joined the aerospace degree was because I was interested in CFD. But since I could't land any...
35. ### CFD:Symmetry in Lagrangian

Hi guys, have a very tricky question on my HW to find compact group of global symmetry to this Lagrangian of 2 complex scalar fields L={\partial_\mu \phi_1^*}{\partial_\mu \phi_1}+{\partial_\mu \phi_2^*}{\partial_\mu \phi_2}-\lambda(\phi_1^* \phi_1 - \phi_2^* \phi_2 - v^2)^2 and I can't figure...


text:
# Trial division + Miller-Rabin complexity

I was reading a paper that shows time complexity of Trial division + Miller-rabin test for creating prime number.

T = N(T_rnd + T_td + T_mr)

T_rnd denotes time for making rnd number, T_td denotes time for trial division, and T_mr denotes time for Miller-rabin test.

N denotes the number of r(n-bit random number) that algorithm make until r is a prime number. Which is nln2/2.

I can't calculate how nln2/2 comes out.

Anyone can help me to understand this?

and sry for my bad English.

Well, the probability that a random number circa $$N$$ happens to be prime is approximately $$1 / \log_e N$$ (for $$e=2.718281828...$$), this is also known as $$1 / \ln N$$.
Now, if $$n$$ is the number of bits of the number we're searching for, that is, we are generating random numbers circa $$2^n$$, then this probability is approximately $$1 / \ln 2^n = 1 / (n \ln 2)$$. Hence, if we try random $$n$$ bit numbers, we would expect to need to try about the inverse of this number, namely $$n \ln 2$$, before we stumble onto a prime. Now, obviously, we might get lucky early, or we might happen to need to do several times this number before we find a prime - this is just an average.
Now, one thing that you don't mention that they do is, when they select a random number, they set the lsbit. This means that we'll never select an even number (which are hardly ever prime), effectively doubling the probability that a guess happens to give us a prime. This doubling of the probability halves the number of expected trials, hence giving us an expected $$n \ln 2 / 2$$ trials.
Now, one thing about the equation you listed; it includes the term $$N T_{mr}$$. This may be accurate if, independent of whether the trial division finds a factor or not, you perform the Miller-Rabin test anyways. However, it is more likely that, if the trial division shows that the number is composite, you don't perform the Miller-Rabin test, but instead try again with another random number. This implies that you perform fewer Miller-Rabin tests than the number of random numbers you picked (and how much fewer would depend on how thorough you are with your trial division; checking the factors 3, 5, 7 will be less effective (but cheaper) than checking all potential prime factors less than, say, a million).