text:
## Dolby Vision now possible through MP4 Mux.

Please post here for issues related to UHD discs
kws53
Posts: 22
Joined: Sun May 04, 2014 9:09 pm

### Re: Dolby Vision now possible through MP4 Mux.

I did some software experimentation...
Using MI Fallout (DV + Atmos), I looked at the following:
1) Demuxing with EAC3TO - although it listed the EL as track 3, when all was demuxed, the EL layer was left behind. I could manually demux this layer later.
2) Demuxing with TSMuxer:
a) Using the Stream to demux, both the BL and EL were checked off to be demuxed.
b) Using the Playlist to demux (same length), only the BL was checked off to be demuxed.
3) Demuxing with FFMpeg - using the method in this thread, the EL and BL HEVC files were identical to the h265 files created by EAC3TO.
4) The Dolby VES muxing operation described in this thread worked flawlessly on both the BL/EL HEVC and the EAC3TO h265 files.
5) The final MP4 muxing operation (GPAC 0.80) was unsuccessful despite having 1TB of space available on the U: drive.
Attachments
GPAC-Issue.png (9.29 KiB) Viewed 4394 times

kazuma
Posts: 53
Joined: Fri Nov 08, 2019 9:51 pm

### Re: Dolby Vision now possible through MP4 Mux.

hello,

the tool of grencola selects french & german as first language when i convert to mp4 with the movies red heat and universal soldier. this because the audio files are first selected standard audio in the container. i tryed to delete all other audio's with tsmuxer, but i get a error code. what is the solution of this?

RESET_9999
Posts: 232
Joined: Mon Aug 05, 2019 7:12 pm

### Re: Dolby Vision now possible through MP4 Mux.

kws53 wrote:
Fri Nov 08, 2019 8:55 pm

5) The final MP4 muxing operation (GPAC 0.80) was unsuccessful despite having 1TB of space available on the U: drive.
if you dont add -tmp U:\ then C:\ is used for the temp files
Sony x700 ----> Denon AVR ----> LG OLED C8

kws53
Posts: 22
Joined: Sun May 04, 2014 9:09 pm

### Re: Dolby Vision now possible through MP4 Mux.

RESET_9999 wrote:
Fri Nov 08, 2019 10:04 pm
kws53 wrote:
Fri Nov 08, 2019 8:55 pm

5) The final MP4 muxing operation (GPAC 0.80) was unsuccessful despite having 1TB of space available on the U: drive.
if you dont add -tmp U:\ then C:\ is used for the temp files
Wasn't aware temp files were created, thank you for the explanation. Since the combined size of the files is ~85GB, I can see the issue...
What exactly is the reason for a temp file anyway? We're simply muxing, aren't we?

Alldu
Posts: 29
Joined: Mon Jun 24, 2019 4:27 pm

### Re: Dolby Vision now possible through MP4 Mux.

Hi guys, I'm trying to add FLAC file to a DV mp4 that I make. I could convert it to AC-3, but then I'd loose the quality? Is there a way to add a FLAC file to a DV mp4 without loosing the quality? I understand there has been found a way to add a lossless audio to a DV mp4 file, but as I tried to follow all the discussions here, I was totally lost like 20 pages ago I use the wonderful dvmp4maker program by Grencola. Any headsup would be very much appreciated!

superfans124
Posts: 32
Joined: Fri Oct 04, 2019 3:26 pm

### Re: Dolby Vision now possible through MP4 Mux.

Alldu wrote:
Sat Nov 09, 2019 11:28 am
Hi guys, I'm trying to add FLAC file to a DV mp4 that I make. I could convert it to AC-3, but then I'd loose the quality? Is there a way to add a FLAC file to a DV mp4 without loosing the quality? I understand there has been found a way to add a lossless audio to a DV mp4 file, but as I tried to follow all the discussions here, I was totally lost like 20 pages ago I use the wonderful dvmp4maker program by Grencola. Any headsup would be very much appreciated!
https://forum.mrmc.tv/viewtopic.php?f=1 ... &start=310

yusesope
Posts: 160
Joined: Sun Jul 28, 2019 3:34 am

### Re: Dolby Vision now possible through MP4 Mux.

The weekend has arrived! It's time to test!

In the last few days I have taken a look at the Google ExoPlayer library (GITHUB).
Today I patched their code to add support for TrueHD/ATMOS tracks inside an MP4 container.
The implementation is far from perfect but is good for testing purposes. For now it should be able to play the most common type of TrueHD/ATMOS track: 8 channels @ 48kHz in L R C LFE Ls Rs Lb Rb configuration.
I also added FFmpeg (ver 4.2) to decode the audio if your device is not equipped with the right Hardware/Software decoder

The ExoPlayer library should be able to play video files with dvhe.05 profile (on devices that are clearly provided with the appropriate decoder + license). So, in theory, it should be possible to play MP4 files with Dolby Vision + TrueHD/ATMOS.

HERE you can find my custom Player.
HERE you can find a sample video (dvhe.05.06 + TrueHD/ATMOS)
I currently don't have any Android devices capable of decoding 4K HDR tracks. For now, I have to stop here: I can't debug the code and fix any problems because I don't have any valid device.

The Player is based on client-server logic:
• Start the server on PC/Mac and follow the instructions (You will find a version already compiled for Windows and the source code for those using Linux/macOS)
• Start the application (apk) on Android.

WARNING!
Being a test version, the server address is hard-coded inside the apk.
HERE a guide for Windows/macOS (those who use Linux know how to take care of themselves )

If for some reason (IP conflict, different subnet, etc..) you need to change the IP of the server:
• Create a folder and place the apk file in it.
• Rename the .apk file to .zip
• Unzip the archive here (not inside a sub-folder)
• delete the original apk
• Go to the "assets" folder and open "media.exolist.json" with a text editor.
• Change the ip address (do not edit after the colon ":") and save
• Go back to the main folder. Open the META-INF folder and delete the existing * .RSA and * .SF files
• Go back to the main folder. Select all the files and create a new zip archive. Make sure the archive is structured as follows: zip-->files&folders and not zip-->sub-folder-->files&folders
• rename the .zip archive in .apk
• Now it is necessary to sign the apk. Who uses Windows can utilize the tool I prepared (HERE). Start the "sign_apk.bat" file and follow the instructions. Who uses Linux/macOS can refer to the project by Patrick Favre-Bulle (GITHUB). HERE you'll find the jar file to use.
• At the end of the process, you will find, in the same folder as the initial apk, a new signed apk file.
VirusTotal Scan
Streaming Server (eight false positives. If your antivirus detects an anomaly, HERE the reason why)
Player
Last edited by yusesope on Tue Nov 12, 2019 11:19 am, edited 1 time in total.

FusionNeo
Posts: 21
Joined: Sat Nov 02, 2019 1:15 pm

### Re: Dolby Vision now possible through MP4 Mux.

Amazing work! I will test this as soon as I can and report my results back.

What do you think of the claim that DVDFab Single Layer files are not “proper” Dolby Vision? As you can see from RESET_9999’s screenshot, the dual layer and UHD look identical but the single layer and UHD have some stark differences. Seems to me that the DVDFab rips may not actually be proper Dolby Vision, which has been the claim fairly early on.

bobross
Posts: 10
Joined: Wed Jun 06, 2018 12:09 am

### Re: Dolby Vision now possible through MP4 Mux.

FusionNeo wrote:
Thu Nov 07, 2019 6:13 am
bobross wrote:
Thu Nov 07, 2019 2:38 am
How can you make the MP4 with movies that only have DTS-HD or DTS Audio, not AC3?
The process is the same. FFMpeg is taking the audio stream you have, ripping it and encoding it into whatever format you want.
Thank you for the suggestion, but when I "startmux.bat" back again the sound is way out of sync. Any way to fix this?

Alldu
Posts: 29
Joined: Mon Jun 24, 2019 4:27 pm

### Re: Dolby Vision now possible through MP4 Mux.

superfans124 wrote:
Sat Nov 09, 2019 2:12 pm
Alldu wrote:
Sat Nov 09, 2019 11:28 am
Hi guys, I'm trying to add FLAC file to a DV mp4 that I make. I could convert it to AC-3, but then I'd loose the quality? Is there a way to add a FLAC file to a DV mp4 without loosing the quality? I understand there has been found a way to add a lossless audio to a DV mp4 file, but as I tried to follow all the discussions here, I was totally lost like 20 pages ago I use the wonderful dvmp4maker program by Grencola. Any headsup would be very much appreciated!
https://forum.mrmc.tv/viewtopic.php?f=1 ... &start=310
Thanks, but that's exactly why I lost it... :/ I dunno, maybe @Grencola updated his wonderful tool for losless audio and I just missed it?..

Grencola
Posts: 343
Joined: Sun Jan 27, 2019 5:19 pm

### Re: Dolby Vision now possible through MP4 Mux.

Alldu wrote:
Sun Nov 10, 2019 12:08 am
superfans124 wrote:
Sat Nov 09, 2019 2:12 pm
Alldu wrote:
Sat Nov 09, 2019 11:28 am
Hi guys, I'm trying to add FLAC file to a DV mp4 that I make. I could convert it to AC-3, but then I'd loose the quality? Is there a way to add a FLAC file to a DV mp4 without loosing the quality? I understand there has been found a way to add a lossless audio to a DV mp4 file, but as I tried to follow all the discussions here, I was totally lost like 20 pages ago I use the wonderful dvmp4maker program by Grencola. Any headsup would be very much appreciated!
https://forum.mrmc.tv/viewtopic.php?f=1 ... &start=310
Thanks, but that's exactly why I lost it... :/ I dunno, maybe @Grencola updated his wonderful tool for losless audio and I just missed it?..
I suppose I probably should, hey? it really wouldn't be very hard. never seem to have any time these days though

DaMacFunkin
Posts: 136
Joined: Tue Oct 30, 2018 4:17 pm

### Re: Dolby Vision now possible through MP4 Mux.

yusesope wrote:
Sun Nov 03, 2019 10:24 am
RESET_9999 wrote:
Sat Nov 02, 2019 7:58 pm
it works, AVR show atmos with my htpc.
FusionNeo wrote:
Sun Nov 03, 2019 1:16 am
The new file you just posted has proper ATMOS support too when played back on a HTPC using your tutorial. Confirmed I am getting ATMOS audio and I was able to hear sound come out of my ATMOS speakers.
Thank you both for your feedback.
RESET_9999 wrote:
Sat Nov 02, 2019 7:58 pm
I tried again with a movie and it works with the htpc. i wonder why it didnt work when i tried a couple days ago(didnt update any software since then)
it's magic!
FusionNeo wrote:
Sun Nov 03, 2019 1:16 am
Yusesope, you are the man!
Thanks but the credit also goes to the user likeadoc (look HERE).
FusionNeo wrote:
Sun Nov 03, 2019 1:16 am
Just tried the new Plex beta out on my Shield 2019 with your Dolby Vision DTS-X and DTS-HD MA and both files played back in Dolby Vision with DTS-X and DTS-HD MA audio.
I assume, the Single Layer files. Excellent news anyway!
FusionNeo wrote:
Sun Nov 03, 2019 1:16 am
That same file will NOT play back on my NVIDIA Shield vía Plex...Do the PLEX devs need to add support?
Correct . We must inform the developers (Plex, MrMC, etc.) about the existence of this possibility and they will implement the correct decoding (as did the developers of LAV Filters).
FusionNeo wrote:
Sun Nov 03, 2019 1:16 am
Once this file plays back on the SHIELD, then I would assume it would be trivial to use a Dolby Vision video track in place of the video track you used in that file for full TRUEHD + Dolby Vision support, is that correct?
Correct again. I've just updated my "HOW TO".
Sorry if this is a stupid question, what if there are dummy or obsvicated playlists? How does ffmpeg know which one to choose when you rip the dts-hd?
Thank you.

yusesope
Posts: 160
Joined: Sun Jul 28, 2019 3:34 am

### Re: Dolby Vision now possible through MP4 Mux.

For those who are experimenting problems with out-of-sync audio, it is advisable to update the tools used to the latest version. In particular MP4box. HERE you can find the latest version (already compiled for all operating systems).
DaMacFunkin wrote:
Fri Nov 08, 2019 6:54 am
Should I just have subs as an external srt?
I've always preferred text subtitles instead of bitmaps.
Keep it simple: use an external .srt renamed as the video file.
If you really want to incorporate the subtitle into the video file, convert the .srt file

Code: Select all

ffmpeg -i sub_in.srt -map 0:0 -c mov_text sub_out.3gp
and then, during the last mux phase, add to the MP4box command line:

Code: Select all

-add sub_out.3gp#subtitle:lang=ita
DaMacFunkin wrote:
Fri Nov 08, 2019 6:54 am
And what about chapters, is is safe to add these to the mp4 with an header editor?
The IsoMedia file format does not include the addition of chapters to an MP4 file as standard; don't be surprised if some players don't understand them.
• Extract the chapters from the source. Use chapterEditor (Convert -> Select Source -> Save as OGG/OGM)
• during the last phase of mux, add to the command line of MP4box:

Code: Select all

-chap \path\to\chapterEditor_output.txt
DaMacFunkin wrote:
Sun Nov 10, 2019 7:38 am
what if there are dummy or obsvicated playlists? How does ffmpeg know which one to choose when you rip the dts-hd?
To my knowledge, FFmeg does not incorporate any de-obfuscation mechanism.
When I need, I use THIS METHOD and then I insert the correct mpls sequence in the FFmpeg command line (as explained in THIS post).
FusionNeo wrote:
Sat Nov 09, 2019 7:55 pm
Seems to me that the DVDFab rips may not actually be proper Dolby Vision
I have the same feeling.

If you are interested in this topic, go and vote for FusionNeo's request on the Plex forum even if you don't use it.
If Plex implements this feature, the other software houses will follow suit.

DaMacFunkin
Posts: 136
Joined: Tue Oct 30, 2018 4:17 pm

### Re: Dolby Vision now possible through MP4 Mux.

I have made a dual layer and a single layer with dvdfab off fate of the Furious and played them both back on my LG C7, there really is no difference, the light out-put looks the same, cyan, yellows and greens have the same tint, nothing is ‘obviously’ different at all,I like to think I have a very critical eye.

Alldu
Posts: 29
Joined: Mon Jun 24, 2019 4:27 pm

### Re: Dolby Vision now possible through MP4 Mux.

Grencola wrote:
Sun Nov 10, 2019 1:14 am

I suppose I probably should, hey? it really wouldn't be very hard. never seem to have any time these days though
You should shouldn't you? That would be so awesome! So let's just hope that one day you'll have some time to do just that!

But can I ask you a question? What would be the best way to add an ac-3 file to mp4 which hasn't been in the original mt2s? I tried to demux the blu ray, extract both HDR10 and DV video layers and drop them all into an mkv together with the ac-3 audio I wanted to add. But when I tried using your dvmp4maker programm to make a DV mp4 out of the mkv, it gives me the error - there's no Dolby Vision. So what went wrong exactly?


text:
### Circumference and area

Two of the most basic formulas regarding circles are the formulas for area and circumference.  The area of a circle is the number of square units that it takes to fill the inside of the circle.  The circumference of the circle is the distance around the circle.  We state two definitions:

DEFINITION:  For a circle with radius r, the area A of the circle is given by

$$A = \pi {r^2}$$

DEFINITION:  For a circle with radius r, the circumference C of the circle is given by

$$C = 2\pi r$$

We can use these two formulas to find areas and circumferences of circles.  Let’s try it out.

Example:  Find the area of the circle whose diameter is 20 inches.

Solution:  Before we can find the area of this circle, we need to know its radius.  But since the radius is equal to half the diameter, we can conclude that

$$r = \frac{1}{2}\left( {20} \right) = 10$$ inches

Then, using the formula for area, we have

$$A = \pi {r^2} = \pi \left( {{{10}^2}} \right)$$

Using the calculator’s value for $$\pi$$, we can approximate this as

$$A = \left( {3.141592654} \right)\left( {{{10}^2}} \right)$$
$$= \left( {3.141592654} \right)\left( {100} \right)$$
$$= 314.2{\text{i}}{{\text{n}}^2}$$

Example:  Find the area of the circle with diameter 16m.

Solution:  Again, we need to obtain the radius of this circle.  Since the radius is equal to half the diameter, we know that $$r = 8$$. Then, using the formula for area, we have

$$A = \pi {r^2}$$
$$= 3.141592654 \times {8^2}$$
$$= 3.141592654 \times 64$$
$$= 201.1{\text{}}{{\text{m}}^2}$$

3475 x

Find the circumference of each circle. Use your calculator's value of π. Round your answer to the nearest tenth.

This free worksheet contains 10 assignments each with 24 questions with answers.

Example of one question:

Watch bellow how to solve this example:

2758 x

Find the area of each. Use your calculator's value of π. Round your answer to the nearest tenth.

This free worksheet contains 10 assignments each with 24 questions with answers.

Example of one question:

Watch bellow how to solve this example:

2603 x

Find the circumference of each circle.

This free worksheet contains 10 assignments each with 13 questions with answers.

Example of one question:

Watch bellow how to solve this example:

### Geometry

Circles
Congruent Triangles
Constructions
Parallel Lines and the Coordinate Plane
Properties of Triangles

### Algebra and Pre-Algebra

Beginning Algebra
Beginning Trigonometry
Equations
Exponents
Factoring
Linear Equations and Inequalities
Percents
Polynomials

format: plain


text:
# polynomial regression pros and cons

Making statements based on opinion; back them up with references or personal experience. Linear and polynomial both have their pros and cons, but one isn’t necessarily better than the other. For example, when you look in the list of polynomials you'll see both 'Second order polynomial' and 'Centered second order polynomial'. 2- Proven Similar to Logistic Regression (which came soon after OLS in history), Linear Regression has been a […] But fear not, he swiftly turns around to show a chart and formulas and also explains linear regression that way. On the other hand, tons of factors are involved in forming a protein structure, therefore ML would show its advantage over mechanistic models in predicting protein structures, especially when we have lots of data at hand. Thanks for contributing an answer to Cross Validated! But this time using Ridge with an Alpha = 0.001. Find an answer to your question “Compare the two methods that you learned for finding or approximating solutions to polynomial equations. Pros: Works well with a large number of features. My new job came with a pay raise that is being rescinded. How centered models are implemented in Prism Xmean is constant, and not a parameter that Prism tries to fit. Even when the X values are not large, the parameters of the model are intertwined, so have high covariance and. Why is it easier to handle a cup upside down on the finger tip? We gloss over their pros and cons, and show their relative speed. That is, the models can appear to have more predictive power than they actually do as a result of sampling bias. Viewed 499 times 2 $\begingroup$ When ... Multivariate orthogonal polynomial regression? Polynomial Features and Regularization Demo - Part 1 20:50 Polynomial Features and Regularization Demo - Part 2 11:15 In practice, ... Pros & Cons. (low lambda) on the features, the model will resemble linear regression model., Linear regression pros and cons; Linear regression in scikit-learn; Interpreting model coefficients; Making predictions; Model evaluation metrics for regression;. Linear Regression and Spatial-Autocorrelation. I would like to represent in one single graph two polynomial regressions and their respective prediction intervals: one for the M1 factor and one for the M2 factor. The main problem here, is the need to understand the correlation of data beforehand. In Monte Carlo experiments, we compare U-MIDAS to MIDAS with functional distributed lags estimated by NLS. The parameters have different meanings, so have different best-fit values (except the first parameter which is the same), different standard errors and confidence intervals, smaller covariances and dependencies, and tighter confidence/prediction bands. Solution Use local polynomial representations such as piecewise-polynomials and splines. Suppose in a disease outbreak scenario and we want to estimate number of infected people based infections over time. The guidelines below are intended to give an idea of the pros and cons of MARS, but there will be exceptions to the guidelines. Polynomial Regression allows for a non-linear relationship to be found. Each of these procedures has pros and cons; whichever is chosen, however, a major question arises on what is the correct polynomial space to use. Thus polynomials may not model asympototic phenomena very well. Accordingly, the sum-of-squares is the same, as are results of model comparisons. We … what are the advantages of using some complicated model such as SIR model from ODE? Here XC is the centered X value, equal to the X value minus Xmean, which  is the mean of all X values. In this sample, we have to use 4 libraries as numpy, pandas, matplotlib and sklearn. We recommend always choosing one of the centered equations instead of an ordinary polynomial equation. Albeit one calculation won't generally be superior to another, there are a few properties of every calculation that we can use as a guide in choosing the right one rapidly and tuning hyper parameters. Alternatively, they can be calculated by the array formula =RidgePred(A2:D19,A2:D19,E2:E19,H9) as defined below, or by the array formula =RegPredCC(A2:D19,H2:H6). Equation 4-9 shows the closed-form solution, where A is the (n + 1) × (n + 1) identity matrix, 11 except with a 0 in the top-left cell, corresponding to the bias term. How are states (Texas + many others) allowed to be suing other states? The predictions for the input data are shown in column J. They are not naturally flexible enough to capture more complex patterns, and adding the right interaction terms or polynomials can be tricky and time-consuming. Intuitively you want to fit function that (in some sense) looks like your underlying process. What makes linear regression with polynomial features curvy? onto a polynomial space (regression procedure). Fitting the centered model leads to exactly the same curve (unless the regular  approach led to math errors). Pros: Simple to implement, works well without a lot of data and easy to interpret. The Decision Tree algorithm is inadequate for applying regression and predicting continuous values. Say you have a round hole, and need to fit a cork into it. It is used to predict the probability (p) that an event occurs. What are the pros and cons to fit data with simple polynomial regression vs. complicated ODE model? Pros and Cons of this augmentation Pros Can model more complicated decision boundaries. There are other ways of statistical extrapolation, but don’t worry about those. CALLAHAN CONS OTC Stock Forecast is based on your current time horizon. Here the model assumes that the independent variables are polynomially correlated to the dependent variable. What spell permits the caster to take on the alignment of a nearby person or object? Does Abandoned Sarcophagus exile Rebuild if I cast it? That is: you are fitting either a particular function or functional form. Uploaded By SL2013. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Polynomial regression can have multiple entries in the normal equation and it is not easy to say which polynomials you have to use in advance. This means that if your data is not a good fit for that particular form, then you will not get good predictions. In fact, the values in range J2:J19 can be calculated by the array formula =H2+MMULT(A2:D19,H3:H6). What is the origin of Faerûn's languages? Least Squares Estimate of Infection Model Parameters, Maximum Likelihood Estimate of Infection Model Parameters. In this paper, we discuss the pros and cons of unrestricted lag polyno-mials in MIDAS regressions. The advantage is extrapolation beyond a specific data set, and the disadvantage is that you have to do maths. Ingo discusses the basics of linear regression and the pros and cons of using it for machine learning. Although one algorithm won’t always be better than another, there are some properties of each algorithm that we can use as a guide in selecting the correct one quickly and tuning hyper parameters. I want to use ggplot() function (which is in package ggplot2 in R). Chapters 4 and 5 describe in detail the use of fractional polynomials for one vari-able. Logistic Regression performs well when the dataset is linearly separable. Even if the program doesn't report any math error, the results can be inaccurate. The advantages of centered polynomial regression. 13. Why we cannot simply fit the data with some polynomials (or some MLP neural network)? Some example polynomials are sin, cos, quadratic, etc. So, overfitting, can regularization come to save? Last modified January 1, 2009. Polynomial basically fits wide range of curvature. Implementations: Python / R; 1.2. How can a linear model fit non-linear data? On the grand staff, does the crescendo apply to the right hand or left hand? Cons. Logistic regression is less prone to over-fitting but it can overfit in high dimensional datasets. Figure 1 – Ridge regression predictions. It only takes a minute to sign up. Based on the number of participating households and collection sites in that data set, the simulation was configured to include 101076 used cooking-oil generator agents, 10 … The advantages of centered models In statistics, polynomial regression is a form of regression analysis in which the relationship between the independent variable x and the dependent variable y is modelled as an n th degree polynomial in x. Polynomial regression fits a nonlinear relationship between the value of x and the corresponding conditional mean of y, denoted E (y | x). If the data is really come from normal distribution or mostly satisfy model assumptions, then fitting the data to normal distribution is better than non-parametric estimation. Ozone data Pros and cons of automated selection Introduction Polynomial regression Interactions Quadratic effects and interactions A final question: given that we have evidence of an interaction between wind and temperature and evidence of nonlinear effects, should we consider a model with both? New to Prism 5.02 (Windows) and 5.0b (Mac) is a set of centered polynomial equations. Most mathematical functions that satisfy reasonable conditions can be approximated by a Taylor series which is a ploynomial. Quadratic and high-degree polynomial regression analysis; Segment data into training and testing; Test models per regression type (Linear, Quadratic, Sextic) Part 1: Pull in data, visualize, and preliminary analyses. Use MathJax to format equations. Can model more complicated regression relationships. What's wrong to fit periodic data with polynomials? Polynomial regression can easily overfit a dataset if the degree, h, is chosen to be too large. ... From this point, logistic regression GAMs share all the same pros and cons as their linear regression counterparts. The primary goal of machine learning is to find a model which can approximate well the underlying patterns of observed data, when we don't have much knowledge about the target system or there are too many entangled parts of the system. Some coefficients will be positive and some negative, so the value of Y depends on subtracting huge numbers from other huge numbers, leading to imprecise results. Polynomial regression with multilevel data. Polynomial Regression [4] Pros. To build sensible mechanistic models we will need good knowledge of the real system. We … However, polynomial regression has a couple drawbacks: 1. So next we're going to want to bring in regularization. Cons: Convergence depends on learning rate and GD type. Just extend time a little bit, we can see how terrible is the polynomial fit: From machine learning perspective, we say the polynomial fit is overfitting. However, the centered equation has reparameterized the model. Polynomial regression extends the linear model by adding additional predictors obtained by raising each of the original predictors to a power. Polynomial models have a shape/degree tradeoff. Weaknesses: Linear regression performs poorly when there are non-linear relationships. Linear Regression vs. We … We discuss 8 ways to perform simple linear regression in Python ecosystem. You should consider Regularization (L1 and L2) … Advice on teaching abstract algebra and logic to high-school students. Can we calculate mean of absolute value of a random variable analytically? No coding required. Feature parameter, e.g., degree of polynomial in linear regression Regularization parameter, e.g., C in SVM Size of training examples Handling skewed/unbalanced classes. As a result, we will get loss minimized / perfect fit for training data. This can be done as part of nonlinear regression,  using this model: Pros and Cons of Regression. Show activity on this post. Polynomial Regression with Python. Linear Regression Chris Albon. Stack Exchange network consists of 176 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.             XC = X - Xmean. Will need good knowledge of the relationship between dependent and independent variable here, is chosen to be too.. Models enable us to investigate ideas for generating scientific hypotheses to bring in regularization feature as new features movement the! Company for its market price how would i connect multiple ground wires in paper. To Cumulative data present your scientific work easily with GraphPad Prism learned for finding or approximating solutions polynomial... ( i think you will not get good predictions paste this URL into your RSS.. Ground wires in this sample, we compare U-MIDAS to MIDAS with functional distributed lags estimated by.... ( Texas + many others ) allowed to be too large 49 ( 3:! A Complete Guide with Python Scikit-Learn system to make sensible assumptions such that the independent variables are correlated... Show their relative speed gloss over their pros and cons to each ML algorithm that we can handle! Lot of data and easy to interpret centering is to subtract the mean of absolute value a. More complicated Decision boundaries infected people based infections over time low and it might not accurately reflect the of. Different nodes in a disease outbreak scenario and we want to bring in regularization infected people based infections over.! Y to create higher order polynomial equations and 1 ): both go. Estimated by NLS Multivariate orthogonal polynomial regression vs. extreme learning machine perfect fit for that form. Wires in this case ( replacing ceiling pendant lights ) cork is square it 's to... Parameters to estimate Post your answer ”, you agree to our terms of service, privacy policy and policy. If i cast it any math error, the output is 1 else 0 promise of achieving three... To handle a cup upside down on the Top 5 Decision Tree algorithm inadequate! Can look here for a non-linear relationship to be too large polynomials sin... Well without a lot of data and easy to interpret after we explain linear regression in an older version Prism. Error and maximize rsquared fitting vs. polynomial fitting is very similar to the nth-degree to minimize the with! Reflect the movement of the model can still capture the essentials representations of the centered instead. Round hole, and not a good model price movement is usually misleading main problem here, is the X! Be written in a networked Compartmental model ( which can still capture the essentials representations of polynomial. 'An ' be written in a networked Compartmental model ( SIR ) for different regimes and... Mse loss convex = > guarantee of a nearby person or object other states relationship to too... A 4 degree polynomial regression and response surface analysis were used to examine the relationship between the Y values the. Unrestricted lag polynomials in MIDAS regressions in detail the use of fractional polynomials one... So part 3, we have to use 4 libraries as numpy,,. ' and 'an ' be written in a list containing both exile Rebuild if cast! Sum-Of-Squares is the polynomial regression pros and cons pros and cons, SIR fitting vs. polynomial fitting is very to! Apply to the right hand or left hand new to Prism 5.02 ( Windows ) 5.0b! Classes ( 0 and 1 ) would always favor ODE if it is used to predict the (. Squares is a set of centered polynomial equations just forcefully take over a public company for its price... Ideas for generating scientific hypotheses recovery codes for 2FA introduce a backdoor polynomial both have their pros and to... I connect multiple ground wires in this paper, we compare U-MIDAS to with... Regression on using the data for a non-linear relationship to be suing other '... In Monte Carlo experiments, we discuss the pros and cons of unrestricted lag in! Decision boundaries Squares estimate of Infection model parameters any case, there are other ways statistical... Use it in machine learning to your Question “ compare the two methods that you for. Model comparisons against other states however, the models can appear to have more less! Data is not included, then 0 has no interpretation handover of work boss. But this time using Ridge with an Alpha = 0.001 is it easier to handle a cup upside on... Contributions licensed under cc by-sa here, is the distance of any X value, equal to the classes! Your current time horizon model effectively an empirical model ( SIR ) different... Choosing mechanistic modeling if it is quite reasonable to approximate an unknown function by a.... Your underlying process: add powers of each feature as new features and worse interpretability in comparison to modeling. Is, the parameters of the polynomial in your regression is used to predict the probability value to epidemiological! A pay raise that is being rescinded applying regression and predicting continuous values before the! System and good observations what are the advantages of using polynomial regression adding predictors. Best for all situations have lots of features you can not simply fit SIR... = X - Xmean denominator, we have to do maths 2FA introduce a backdoor to 5.02... The dataset is linearly separable correlation of data and easy to interpret extreme learning machine codes for 2FA polynomial regression pros and cons! All situations as guidance based polynomial regression pros and cons a set of centered polynomial equations it should come after we explain regression! $\gamma$ in ( Susceptible, infected, Recovered ) SIR model cancel out extreme! Three of these goals Question “ compare the two methods that you learned for finding or solutions...... little spoiler: odes, piecewise polynomials and regularization biological laws, and the X values that way service. Empirical model ( SIR ) for different regimes i want to estimate as direction polynomials... Degree polynomial regression vs. complicated ODE model watch a video on Gradient Descent from Scratch in.! This means that if your data is not a parameter that Prism tries to fit like most models. Lags estimated by NLS ( Texas + many others ) allowed to be too.... Following biological laws, and show their relative speed want to bring in regularization of work, boss 's asks... Shown in column J distance of any X value, equal to the dependent variable making statements based on nth... You open a file using centered polynomial equations enable us to investigate ideas generating. In regularization don ’ t worry about those of using some complicated model such as piecewise-polynomials splines! | software testing, software testers experience different levels of testing round,! On  parametric model vs. non-parametric model '' of features you can fit to.


text:
# Good references for Rigged Hilbert spaces?

Every now and then I attempt to understand better quantum mechanics and quantum field theory, but for a variety of possible reasons, I find it very difficult to read any kind of physicist account, even when the physicist is trying to be mathematically respectable. (I am not trying to be disrespectful or controversial here; take this as a confession of stupidity if it helps.) I am generally interested in finding online mathematical accounts which ideally would come close to being of "Bourbaki standard": definition-theorem-proof and written for mathematicians who prefer conceptual explanations, and ideally with tidy or economical notation (e.g., eschewing thickets of subscripts and superscripts).

More specifically, right now I would like a (mathematically trustworthy) online account of rigged Hilbert spaces, if one exists.

Maybe I am wrong, but the Wikipedia account looks a little bit suspect to me: they describe a rigged Hilbert space as consisting of a pair of inclusions $i: S \to H$, $j: H \to S^\ast$ of topological vector space inclusions, where $S^\ast$ is the strong dual of $S$, $H$ is a (separable) Hilbert space, $i$ is dense, and $j$ is the conjugate linear isomorphism $H \simeq H^\ast$ followed by the adjoint $i^\ast: H^\ast \to S^\ast$. This seems a little vague to me; should $S$ be more specifically a nuclear space or something? My guess is that a typical application would be where $S$ is Schwartz space on $\mathbb{R}^4$, with its standard dense inclusion in $L^2(\mathbb{R}^4)$, so $S^\ast$ consists of tempered distributions.

I also hear talk of a nuclear spectral theorem (due to Gelfand and Vilenkin) used to help justify the rigged Hilbert space technology, but I don't see precise details easily available online.

-

Some time ago I was interested in rigged Hilbert space to get a better understanding of quantum physics. On that occasion I collected some references on this subject, see below. It's quite comprehensive. A good starting point for an overview could be the works of Madrid and Gadella. Note that there are different versions of "rigged Hilbert space" (in context of quantum physics) in literature.

J.-P. Antoine. Dirac formalism and symmetry problems in quantum mechanics. i. general dirac formalism. Journal of Mathematical Physics, 10(1):53--69, 1969.

N.Bogoliubov, A.Logunov, and I.Todorov. Introduction to Axiomatic Quantum Field Theory, chapter 1 Some Basic Concepts of Functional Analysis 4 The Space of States, pages 12--43, 113--128. Benjamin, Reading, Massachusetts, 1975.

R.de la Madrid. Quantum Mechanics in Rigged Hilbert Space Language. PhD thesis, Depertamento de Fisica Teorica Facultad de Ciencias. Universidad de Valladolid, 2001. (available here)

M.Gadella and F.Gómez. A unified mathematical formalism for the dirac formulation of quantum mechanics. Foundations of Physics, 32:815--869, 2002. (available here)

M.Gadella and F.Gómez. On the mathematical basis of the dirac formulation of quantum mechanics. International Journal of Theoretical Physics, 42:2225--2254, 2003.

M.Gadella and F.Gómez. Dirac formulation of quantum mechanics: Recent and new results. Reports on Mathematical Physics, 59:127--143, 2007.

I.M. Gelfand and N.J. Vilenkin. Generalized Functions, vol. 4: Some Applications of Harmonic Analysis, volume4, chapter 2-4, pages 26--133. Academic Press, New York, 1964.

A.R. Marlow. Unified dirac-von neumann formulation of quantum mechanics. i. mathematical theory. Journal of Mathematical Physics, 6:919--927, 1965.

E.Prugovecki. The bra and ket formalism in extended hilbert space. J. Math. Phys., 14:1410--1422, 1973.

J.E. Roberts. The dirac bra and ket formalism. Journal of Mathematical Physics, 7(6):1097--1104, 1966.

J.E. Roberts. Rigged hilbert spaces in quantum mechanics. Commun. math. Phys., 3:98--119, 1966. (available here)

Tjøstheim. A note on the unified dirac-von neumann formulation of quantum mechanics. Journal of Mathematical Physics, 16(4):766--767, 4 1975.

Edit I remember that there is also a discussion about Gelfand triples in physics in the Funktionalanalysis books by Siegfried Großmann but I don't have a copy handy the moment. Though it is in german it might be interesting for you, too.

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Thanks, student. I am not particularly near a good library where I can access these to see which would suit my purposes. I remember seeing something by Madrid on the arXiv and it wasn't quite what I was looking for, but I'll look at his thesis. Which of these do you think are in definition-theorem-proof format at a level of rigor that would satisfy mathematicians? – Todd Trimble Oct 23 '10 at 20:18
When I collected the references I was interested to have as much rigor as possible. If I remember correctly all of those are written in a usual mathematical style. In Madrid's thesis there are many examples concerning quantum mechanics. For a more general approach I would look at M.Gadella and F.Gómez. A unified mathematical formalism for the dirac formulation of quantum mechanics. Foundations of Physics, 32:815--869, 2002 In this paper they tried to unify some (perhaps most) versions of rigorous frameworks for rigged Hilbert space in view of quantum physics. – student Oct 23 '10 at 21:20
I think the problem with this subject is, that there are many different attempts to give a rigorous framework for rigged Hilbert spaces in physics. I don't know if there is a generally accepted useful version. Hence it's not surprising that there are now good free online resources about this subject. – student Oct 23 '10 at 21:27
@student: thanks again for all your references, but regarding your last comment, you've so far given me one online resource (Madrid), which gives no proofs. So this is not in a style that I was asking for above. – Todd Trimble Oct 23 '10 at 22:10
I added links to those articles which are currently open access (only two more, sorry) – student Oct 23 '10 at 23:27

"Generalized functions volume 4" by Gelʹfand, Vilenkin, (Math review number 0146653) has a long an detailed discussion of rigged Hilbert spaces and nuclear spaces. The book by Glimm and Jaffe has a brief summary of the theory.

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Thank you, Richard. At physicsforums.com/showthread.php?t=294488 I read some hearsay about some alleged flaws in their arguments; do you know what they're talking about and whether a mathematician should be worried? – Todd Trimble Oct 23 '10 at 17:48

This is not precisely related to your question, but a certain notion of rigged Hilbert space occurs in the theory of C*-algebras. Particularly, one should look at the work of Marc Rieffel, e.g. http://math.berkeley.edu/~rieffel/papers/morita_equivalence.pdf. I figured I'd mention this because it is decidedly mathematical, and a useful idea.

-
Thanks, Jon. Interesting blast from the not-too-distant past. – Todd Trimble Oct 25 '10 at 12:50
You're welcome, Todd! – Jon Bannon Oct 25 '10 at 14:21
Correct me if I'm wrong, but Rieffel's rigged spaces are what we call Hilbert C*-modules, right? Is that related to the rigged spaces everyone here is talking about? I'm asking because I really don't understand... Anyway, if so, a nice book would also be Lance's "Hilbert C*-Modules: A Toolkit for Operator Algebraists", since its a toolkit and all, very concise and extremely pedagogic. – Yul Otani Nov 14 '12 at 19:00
@Yul: I was wondering the same thing way back when I asked this (hence my first sentence). I don't see a direct relation, come to think of it...except via the Gelfand triple bit...but that is not a precise relation. If you happen to find out, please let me know. – Jon Bannon Nov 14 '12 at 23:00

I would highly recommend looking at the chapter on Sobolev Towers in the book by Engel and Nagel One-Parameter Semigroups for Linear Evolution Equations or the "baby edition" A Short Course on Operator Semigroups.

It provides a really nice example of rigged Hilbert spaces. For example, if $A:D(A) \subset L^2 \to L^2$ is the (Dirichlet) Laplacian, then one can identify $D(A^n)$, $n=1,2,\ldots$ with Sobolev spaces and $D(A^{-n})$ with the negative Sobolev spaces (i.e. extrapolation spaces of $A$).

This concept can be taken further if one considers analytic semigroups and fractional powers of operators and also into the Banach space setting (see Amann's book Linear and Quasilinear Parabolic Problems: Abstract linear theory).

Basically, the concept of rigged Hilbert spaces becomes really natural if one keeps PDEs and Sobolev spaces in mind.

Finally, the book by Reed and Simon Methods of Modern Mathematical Physics - Vol 1: Functional analysis provides a number of references for rigged Hilbert spaces at the end of Section VII (page 244).

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Thank you, Dale! I have Reed and Simon, which I have studied from time to time (and also have taught with) but somehow missed those references at the end of chapter VII. Must be the reduced-size font. – Todd Trimble Nov 22 '10 at 13:46
No problem. It's a great book :) – Dale Roberts Nov 24 '10 at 1:45
Just wanted to let you know that this answer has been very useful for my research, thanks! Also, Nagel's exposition of Sobolev towers can be accessed online in his paper: kurims.kyoto-u.ac.jp/~kyodo/kokyuroku/contents/pdf/1009-14.pdf – Giuseppe Negro Apr 14 at 9:48

The Springer online Encyclopedia of Mathematics' entry on RHS looks more rigorous albeit also more succinct than Wikipedia; for another online intro see the nlab entry. In addition to the references listed there, a rigorous discussion of the RHS can be found (as far as I recall -- I do not have a copy handy) e.g. in the two-volume book Principles of Advanced Mathematical Physics by Robert D. Richtmyer. Also, it appears that, unlike the physics community, the name Gelfand triple (rather than RHS) is more commonly used by the mathematicians.

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Thanks for the tips, mathphysicist. The first sentence of that Springer Encyclopedia reference gives the same definition as wikipedia (so maybe that definition is perfectly adequate after all), but then a little later it says, "The most interesting case is that in which is $\Phi$ [my $S$] is a nuclear space." Then they cite a spectral theorem, but I can't tell if they mean to include the nuclear hypothesis in the theorem or not. – Todd Trimble Oct 23 '10 at 17:27
Um, mathphysicist, I know you don't realize it, but I was the one who wrote (most of) that nLab article! – Todd Trimble Oct 23 '10 at 20:09
Well, Todd, unfortunately I didn't, sorry :( Should have looked at the edits history :) – mathphysicist Oct 24 '10 at 2:24
Please feel free to remove the nLab reference from my answer if you find this necessary and/or appropriate. – mathphysicist Oct 24 '10 at 2:25

I would add A.Bohm and M.Gadella, Dirac Kets, Gamow Vectors and Gel'fand Triplets, Springer Lecture Notes in Physics, vol. 348 (Springer, Berlin, 1989) http://link.springer.com/book/10.1007%2F3-540-51916-5

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The truth is that an actual rigorous theory of rigged hilbert space doesn't exist at all. That's the bitter truth. Unfortunately we have been told for many years to don't worry, that this theory was exsisting, somewhere. However it looks like this is a mithology....I did many investigations for many years.

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Could you comment then on why, for you, Gelfand-Vilenkin falls short? As it stands, this answer is not very useful to me, but if you could comment on this it might become much more useful. – Todd Trimble Jul 12 '15 at 9:40


text:
Part One : Work systematically - look at $1$ multiplying something, then at $2$ multiplying the same number, then $3, 4$ and so on.

Part Two : If this wasn't possible to do, how could you show that it was impossible?

Part Three : Start with a smaller version of the same kind of grid, perhaps having only $1, 2$ and $4$ with which to make each factor.


text:
# Invert a list / map

Often we use lists to map keywords onto values, for example

foo <- list(a=c("quark", "fark"),
b=c("quark", "foo", "bark"),
c=c("fark", "bark"))

To invert this list (such that “fark”, “bark” etc. become keywords, and “a”, “b” and “c” the values), do

foo.rev <- split(rep(names(foo), lengths(foo)), unlist(foo))

split splits a vector or data frame along a factor. In this case, we expand the names of foo using rep such that we get two vectors, as can be seen with the following command:

cbind(rep(names(foo), lengths(foo)), unlist(foo))

with the result

   [,1] [,2]
a1 "a"  "quark"
a2 "a"  "fark"
b1 "b"  "quark"
b2 "b"  "foo"
b3 "b"  "bar"
c1 "c"  "fark"
c2 "c"  "bar"

When we apply split() to the first vector with the second to guide the split, we will get

$bar [1] "b" "c"$fark
[1] "a" "c"

$foo [1] "b"$quark
[1] "a" "b"


text:
# Still stuck on orthogonalisation

#### Hamlings

Hi all

Still stuck on a problem involving Gram-Schidmt process, to find an orthogonal basis for T that includes the vector (1, 0, 0, 2).

set T = {(x, y, z, 2x + y − 3z) : x, y, z ∈ R}.

Would appreciate any help you could give me.

Thanks.

#### Greens

First, we need a basis for $T$. This can be found by finding the matrix representation of $T$ and using the linearly independent columns.

We know $T: \mathbb{R}^3 \mapsto \mathbb{R}^4$. Let $\alpha$ and $\beta$ be the standard bases for $\mathbb{R}^3$ and $\mathbb{R}^4$ respectively.

$\displaystyle [T]_{\alpha}^{\beta} = \left( \; \; [T(1,0,0)]_{\beta} \; \; [T(0,1,0)]_{\beta}\; \; [T(0,0,1)]_{\beta} \; \; \right)$

$\displaystyle = \begin{bmatrix} 1 & 0 & 0\\ 0 & 1 & 0\\ 0 & 0 & 1\\ 2 & 1 & -3 \end{bmatrix}$

This matrix is already in Echelon Form. Since the columns are linearly independent, we know that those column vectors form a basis for $T$

For the G.S process, we are seeking the orthogonal basis $\{w_1, w_2 , w_3\}$. We start with the required vector $(1,0,0,2)$, which is conveniently included in the basis.

$\displaystyle w_1 = v_1 = (1,0,0,2)$

$\displaystyle w_2 = (0,1,0,1) - \frac{2}{5}(1,0,0,2) = \left(\frac{-2}{5} , 1 , 0 , \frac{1}{5} \right)$

$\displaystyle w_3 = (0,0,1,-3) - \frac{-6}{5}(1,0,0,2) - \frac{-3}{30}(-2,5,0,1) = \left(1,\frac{1}{2},1,\frac{-1}{2} \right)$

#### Hamlings

Thank you very much.


text:
Q

Identify the terms, their coefficients for each of the following expressions. 5xyz^2-3zy

Q : 1        Identify the terms, their coefficients for each of the following expressions.

(i) $5xyz^2-3zy$

The terms are$5xyz^{2}\ and\ -3zy$  and the coefficients are 5 and -3.


text:
Question

# Consider the following balanced equation in which gas X forms gas $\mathrm {X} _ { 2 } :$ 2$\mathrm { X } ( g ) \longrightarrow \mathrm { X } _ { 2 } ( g )$ Equal moles of X are placed in two separate containers. One container is rigid, so the volume cannot change; the other container is flexible, so the volume changes to keep the internal pressure equal to the external pressure. The above reaction is run in each container. What happens to the pressure and density of the gas inside each container as reactants are converted to products?

Solution

Verified
Step 1
1 of 3

$2X \rightarrow X_{2}$

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text:
# Heat , Specific Heat Capacity , Molar Heat Capacity , Latent Heat , Water-Equivalent , Principle of Calorimetry

Heat : When two bodies at different temperature are placed in contact , the energy is transferred from higher temperature to lower temperature known as Heat .

Heat & Work equivalent : The temperature of a body can be increased by supplying heat to it or by doing work . If mechanical work W produces the temperature changes as Heat Q , then

$\large W = J Q$

Where , J = Mechanical equivalent of heat

J = 4.2 J/cal

### Calorie:

The amount of heat needed to increase the temperature of 1 gm of water from 14.5°C to 15.5°C at STP is known as 1 calorie

### Specific Heat Capacity:

It is heat required to raise temperature by 1° C or 1° K for unit mass of the body.

$\large s = \frac{\Delta Q}{m \Delta T}$

$\large \Delta Q = m s \Delta T$

$\displaystyle dQ = m s dT$

$\displaystyle Q = m\int_{T_1}^{T_2} s dT$
(be careful about unit of temperature, use units according to the given units of s )

### Latent Heat:

The amount of heat required to change one phase of 1 gm of a substance to another phase.

Q = m L

L = latent heat of substance in cal/gm or in Kcal/kg.

Lice = 80 cal/gm – Specific latent heat of fusion of ice

Lsteam = 540 cal/gm – Specific latent heat of vaporization of water

### Molar Heat Capacity:

If instead of unit mass we consider one mole of a substance, the heat required to change the temperature of one mole of a substance through 1°C (or K) is called molar heat capacity or molar specific heat and is represented by C.  If the molecular weight of a substance is M :

$\displaystyle C = \frac{Q}{n \Delta T}$

As , $\displaystyle s = \frac{Q}{m \Delta T} \quad and \quad n = \frac{m}{M}$

Its SI units are (J/mol K)

### Thermal-capacity :

If instead of unit mass we consider the whole body, (of mass m), the heat required to raise the temperature of a given body by 1°C is called its thermal capacity , i.e.,

Thermal capacity = $\displaystyle m s = n C = \frac{Q}{\Delta T}$

Thermal capacity of a body depends on the mass and nature of body. It has units (J/K) or cal/°C

### Water-Equivalent :

If thermal capacity of a body is expressed in terms of mass of water it is called water-equivalent of the body,

i.e., water-equivalent of a body is the mass of water which when given same amount of heat as to the body, changes the temperature of water through same range as that of the body, i.e.,

$\displaystyle W = (m \times s )$ gram

[where : W = mass of water ; m = mass of substance ]

The unit of water equivalent W is g while its dimension [M].

### Principle of Calorimetry

When two bodies (one being solid and other liquid or both being liquid) at different temperature are mixed, heat will be transferred from body at higher temperature to a body at lower temperature till both acquire same temperature.

The body at higher temperature releases heat while body at lower temperature absorbs it, so that :

#### Heat lost = Heat gained

i.e. principle of calorimetry represents the law of conservation of heat energy.

Solved Example : The temperature of equal massesof three different liquids A, B and are 12°C, 19° C and 28° C respectively. The temperature when and are mixed is 16° C and when and are mixed is 23° C. What would be the temperature when and are mixed?

Solution: In accordance with principle of calorimetry :

When A and B are mixed

m SA (16 – 12) = m SB (19 – 16)

=> SA = (3/4)SB

and when B and C are mixed

m SB (23 – 19) = m SC (28 – 23)

SC = (4/5)SB

Now when A and C are mixed if T is the common temperature of mixture:

m SA (T – 12) = m SC (28 – T)

Substituting SA and Sc from above,

(3/4)(T – 12) = (4/5)(28 – T)

which on solving gives,

T = 20.25 ° C

Solved Example : A solid material is supplied heat at a constant rate. The temperature of the material is changing with the heat input as shown in figure. Study the graph carefully and answer the following questions :

(i) What do the horizontal regions AB and CD represent?

(ii) If CD = 2 BA , what do you infer?

(iii) What does slope DE represent?

(iv) The slope of OA > the slope of BC .What does this indicate ?

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text:
# Solving a “logistic-like” function with two unknowns, two data points

I am stuck in trying to solve the following:

Given two points $(x_{1}; y_{1})$ and $(x_{2}; y_{2})$, to determine the parameters $a$ and $b$ in the equation:
$$y=\frac{e^{a+bx} - e^{a}}{1+e^{a+bx}}.$$
In other words, I have two unknowns and two set of points, so there's for sure a solution, but how can the following system of equation be rewritten explicitly on $a$ and $b$?

$$\left\{\begin{matrix} y_{1}&=\frac{e^{a+bx_{1}} - e^{a}}{1+e^{a+bx_{1}}}\\ y_{2}&=\frac{e^{a+bx_{2}} - e^{a}}{1+e^{a+bx_{2}}} \end{matrix}\right.$$

Should I implement an equation solver instead? In which case, do you have any suggestion on the method?

Thanks very much, I hope it's not a too stupid question :)

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oops misread your question, never mind – Zarrax Dec 6 '10 at 19:46
can you figure out good initial estimates for $a$ and $b$, should you choose the iterative route? Then Newton-Raphson should do the job. – J. M. Dec 7 '10 at 0:07

I don't know how to solve exactly (or even if it's possible) but maybe this will help: Let $A = e^a$ and $B = e^b$. It suffices to find $A$ and $B$ and then take logarithms. Your two equations can be written as $$y_1 = {A(B^{x_1} - 1) \over 1 + AB^{x_1}}$$ $$y_2 = {A(B^{x_2} - 1) \over 1 + AB^{x_2}}$$ You can solve each of these equations for $A$ via some algebra: $$A = {y_1 \over B^{x_1}(1 - y_1) - 1}$$ $$A = {y_2 \over B^{x_2}(1 - y_2) - 1}$$ So the reciprocals of the right-hand sides are the same (the original equation ensures that $y_1$ and $y_2$ are nonzero): $${B^{x_1}(1 - y_1) - 1 \over y_1} = { B^{x_2}(1 - y_2) - 1 \over y_2}$$ In other words, $${1 - y_1 \over y_1}B^{x_1} - {1 - y_2 \over y_2}B^{x_2} = {1 \over y_1} - {1 \over y_2}$$ This doesn't have a general solution you can write out (for example if $x_1$ and $x_2$ are large positive integers it's a polynomial equation of large degree). But it shouldn't be too hard to deal with numerically. Once you know what $B$ is (or have a good enough approximation) you can plug back in above to get $A$.


text:
# 在VC中使用WMI（英文原版）作者：BugSearcher

## Introduction

We normally find a lot of ways and a number of resources to use WMI or to get information from “Windows Management Instrumentation” while using Visual Basic 6 and C#, but I could not find a single resource describing the same thing in Visual C++. MSDN resources are also very limited in this context.

## Code

Following is the code on how to get the current processor load from a WMI class Win32_Processor defined in a .mof file. .mof files are managed object files which have a typical way of defining classes and methods.

WMI provides the COM service which is used to connect to the WMI services. The important parts of the code include:

• bstrNamespace : The initialization of this variable is very tricky. The first three forward slashes //./ represent the Host Computer name from which you want to get information from. A “.” Indicates that information is to be obtained from the Same Computer on which you are working. You can give any Network name here but getting information from network depends upon your Access Rights etc. cimv2 is the namespace containing the Win32_Processor class.
• pIWbemLocator is the argument in which we get the Interface pointer.
• After that, we call the function ConnectServer of the pIWbemLocator to get a pointer to pWbemServices.
• WMI uses its own Query Language to get information known as WQL (the acronym for WMI Query Language). So, when calling the function ExecQuery, we have to specify the language as its first argument. Second argument is the Query itself. Last argument is important because here we get a pointer to an Enumeration object through which we can enumerate through the objects available. This enumeration is important because consider the case that we want to know the information about running processes and we are using Win32_Process class for this purpose. Then through this enumeration object, we can go through different processes one by one.
• By calling the Reset and Next methods of pEnumObject, we are moving through the objects. We get the pointer to an object in pClassObject.
• The last function through which we get the Actual value of a property is Get. We pass a BSTR to this function to get the value in a Variant.
CoInitialize(NULL);

//Security needs to be initialized in XP first

if(CoInitializeSecurity( NULL,
-1,
NULL,
NULL,
RPC_C_AUTHN_LEVEL_PKT,
RPC_C_IMP_LEVEL_IMPERSONATE,
NULL,
EOAC_NONE,
0
) != S_OK)
return;

IWbemLocator * pIWbemLocator = NULL;
IWbemServices * pWbemServices = NULL;
IEnumWbemClassObject * pEnumObject = NULL;
BSTR bstrNamespace = (L"root//cimv2");
HRESULT hRes = CoCreateInstance (
NULL ,
CLSCTX_INPROC_SERVER | CLSCTX_LOCAL_SERVER ,
IID_IUnknown ,
( void ** ) & pIWbemLocator
) ;
if (SUCCEEDED(hRes))
{
hRes = pIWbemLocator->ConnectServer(
bstrNamespace, // Namespace
NULL, // Userid
NULL, // PW
NULL, // Locale
0, // flags
NULL, // Authority
NULL, // Context
&pWbemServices
);
}
BSTR strQuery = (L"Select * from win32_Processor");
BSTR strQL = (L"WQL");
hRes = pWbemServices->ExecQuery(strQL, strQuery,
WBEM_FLAG_RETURN_IMMEDIATELY,NULL,&pEnumObject);

ULONG uCount = 1, uReturned;
IWbemClassObject * pClassObject = NULL;
hRes = pEnumObject->Reset();
hRes = pEnumObject->Next(WBEM_INFINITE,uCount, &pClassObject, &uReturned);
VARIANT v;
hRes = pClassObject->Get(strClassProp, 0, &v, 0, 0);
SysFreeString(strClassProp);

_bstr_t bstrPath = &v; //Just to convert BSTR to ANSI
char* strPath=(char*)bstrPath;
if (SUCCEEDED(hRes))
MessageBox(strPath);
else
MessageBox(”Error in getting object”);
VariantClear( &v );
pIWbemLocator->Release();
pWbemServices->Release();
pEnumObject->Release();
pClassObject->Release();
CoUninitialize();

## Conclusion

This was the shortest method I was able to work out to get information from any WMI class. You can simply change the class name in the Query and Property Name while calling Get method and you will get information from all the classes supported in your OS. I tested this code in Windows 2000 Professional. I hope it will work well for Win XP but probably not in previous versions of windows because they don’t support a lot of WMI classes.

## Update

I am updating this Article and the code for Windows XP. As I said in the beginning, this was initially intended for Windows 2K and it was still working fine on Windows 2K machine (I have checked it on at least 10 now coz I was getting so many complaints). Well, for Windows XP there is one major change and that was suggested by igoychev. Many thanks for that. The problem with Windows XP was that it needed security to be initialized first. Plus, I have also changed those confusing slashes in bstrNamespace to some simpler ones. I am using Windows 2003 Advance Server and it is working fine on it. You need to include wbemuuid.lib in Project Settings -> Linker -> Additional Dependencies to get this code working. I have also added some error checking to avoid crashes, hope it works for you. You need to have Platform SDK installed for this code to compile. WMI SDK is not necessary once again. Sorry rbervgm, your work was great using WMI SDK but I thought better to keep it WMI SDK Clean. Hope you don't mind. Now, I hope that downloadable project will work for most of the people. One more thing, it still works for Windows 2K machines.

• 本文已收录于以下专栏：

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text:
# Briefing

Sorry for the change of programme. I found, last minute, that doing the eight-point algorithm with uncalibrated views will generate too many problems. We should therefore do a little more with the uncalibrated algorithm.

## Reflection

(This is the same exercise as given yesterday)

Consider the material covered in the sessions 21-22 October.

Do you know,

1. how to calculate 3D co-ordinates of an object point $$p$$, given image points $$x_1$$ and $$x_2$$ in two separate camera frames? What do you require to do so?
2. recover the relative pose of two cameras, given matching image points in the two frames? How many such image points do you require?
3. If the answer is no to either 1 or 2,
• what knowledge do you have to build on?
• what do you need to find out?

# Exercise

Today’s exercise is a repeat of the Eight-point algorithm, but now working off a synthetic data set.

Note. You can choose, in this exercise, how much you want to compute by hand, and what you want to implement in python.

Note that Step 1-3 set up a synthetic data set, and are not part of the solutions for the reconstruction problem.
Instead they illustrate the model for image capture. Step 4-7 solve the reconstruction problem. Because you have a synthetic data set, Step 1-3 actually provides you the ground truth, with which you can compare the solutions found in Steps 6-7.

## Step 1.

Select eight points in general position in 3D. For instance $(-20,0,25), (20,0,25), (0,20,25), (-10,10,50), (10,10,50), (0,-10,50), (0,0,60), (-7,7,70),$ or generate some at random if you prefer.

Note
The exercise has been updated to move the points further from the camera (increasing their $$z$$-coordinates). It seems that at least one point in the first version fell behind the image plane in the rotated camera frame.

## Step 2.

Consider a camera posed in the world frame.
I.e. the selected points have co-ordinates in the camera frame. Assume the image plane has co-ordinates $$z=1$$.

• Find the image point for each world point, using an ideal camera projection.

## Step 3.

Consider a second camere which is translated ten units along the $$x$$-axis and rotated $$30^\circ$$ degrees around the $$y$$-axis. Again the image plane is $$z=1$$.

• Find the transformation (relative pose) $$(R,T)$$.
• Find (3D) co-ordinates in the second camera frame for each world point.
• Find the image points in the second camera frame for each world point.

## Step 4.

Imagine now that we do not know the world points. We are going to try to reconstruct them using the Eight-point algorithm.

1. Construct the matrix $$\chi$$ with the Kronecker products of the eight image pairs.
2. Compute the singular value decomposition of $$\chi=U_\chi\Sigma_\chi V_\chi^T$$ (probably using numpy.linalg.svd)
• Inspect the three components. What do you see?
• The middle component should be a diagonal matrix containing the singular values. How are they ordered?
3. According to Ma (2004:121) the serialised fundamental matrix $$E^s$$ is the ninth column of $$V_\chi$$.
• this should be wrig
4. Unserialise $$E^s$$ to get the preliminary matrix $$E$$.
• you can do this with the numpy reshape function, but test it. You may have to transpose the resulting matrix.

## Step 5. Projection onto the Essential Space

If $$E=U\Sigma V^T$$ is our preliminary matrix as found above, we approximate the essential matrix by replacing $$\Sigma$$ with $$\mathsf{diag}(1,1,0)$$ (cf. Ma (2004:121)).

## Step 6. Rotation and Translation

Recover Translation and Rotation matrices from the essential matrix, relying on Ma (2004:121).

• What do the two solutions represent?
• Do they match the actual transformation?

Remember there are four solutions for $$(R,T)$$, three of which produce objects point behind either or both cameras. Remember to check both $$E$$ and $$-E$$, in addition to the two solutions for $$(R,T)$$ from one choice for $$E$$.

Note If the transformation you find seem off, typically with errors of sign, there are at least two plausible explanations.

1. You have not checked all four solutions (see above).
2. Some object point from Step 1 actually does end up behind the image plane in the second camera frame. If this happens, you should try to choose different object points.

## Step 7. Reconstruction in 3D

Consider one pair of image points together with the transformation $$(R,T)$$.

• Calculating the $$z$$-coordinate $$\lambda$$ of the 3D point as we did in Relative Pose. You know that the distance between the camera origins is $$||T||=10$$.
• Invert the projection to recover the complete coordinates of the 3D point.
• Does the recovered point match the original point?
• If you have time, repeat with a second and possibly a third point. You probably do not want to do all eight, though.


text:
# Are symplectomorphisms of Weil–Petersson symplectic form induced from surface diffeomorphisms?

Let $$S$$ be a closed hyperbolic surface of genus $$g\geq 2$$. Let $$(\mathcal{T},\omega)$$ be the corresponding Teichmuller space with the Weil–Petersson symplectic from $$\omega$$. Let $$\Phi:\mathcal{T}\rightarrow\mathcal{T}$$ be any diffeomorphism which preserves $$\omega$$.

Q) Does there exist a diffeomorphism $$\phi:S\rightarrow S$$ such that the induces map to $$\mathcal{T}$$ is $$\Phi$$?

Any suggestion or reference will be extremely helpful. Thanks in advance.

## 2 Answers

There are infinitely many compactly supported symplectomorphisms of any symplectic manifold, which would then have to be represented by diffeomorphisms of $$S$$ preserving all marked conformal structures, except those in the compact set. But preserving such a conformal structure is only possible for a finite set of diffeomorphisms, as the conformal structure has finite automorphism group.

No, the group of diffeomorphisms isotopic to the identity acts trivially, so what’s left over is the discrete mapping class group. Meanwhile, Wolpert proved that Fenchel Nielsen coordinates are global Darboux coordinates, so the symplectomorphism group of Teichmuller space is isomorphic to the symplectomorphism group of a standard $$\mathbb{R}^n$$. Therefore, surface diffeomorphisms give a tiny fraction of the full group of symplectomorphisms. If you also ask to preserve the complex structure, the answer is yes, at least for genus greater than two by a theorem of Royden.


text:
Properties

 Label 799.1.c.c Level $799$ Weight $1$ Character orbit 799.c Self dual yes Analytic conductor $0.399$ Analytic rank $0$ Dimension $4$ Projective image $D_{8}$ CM discriminant -799 Inner twists $4$

Related objects

Newspace parameters

 Level: $$N$$ $$=$$ $$799 = 17 \cdot 47$$ Weight: $$k$$ $$=$$ $$1$$ Character orbit: $$[\chi]$$ $$=$$ 799.c (of order $$2$$, degree $$1$$, minimal)

Newform invariants

 Self dual: yes Analytic conductor: $$0.398752945094$$ Analytic rank: $$0$$ Dimension: $$4$$ Coefficient field: $$\Q(\zeta_{16})^+$$ Defining polynomial: $$x^{4} - 4 x^{2} + 2$$ Coefficient ring: $$\Z[a_1, \ldots, a_{5}]$$ Coefficient ring index: $$1$$ Twist minimal: yes Projective image: $$D_{8}$$ Projective field: Galois closure of 8.2.8671400783.1

$q$-expansion

Coefficients of the $$q$$-expansion are expressed in terms of a basis $$1,\beta_1,\beta_2,\beta_3$$ for the coefficient ring described below. We also show the integral $$q$$-expansion of the trace form.

 $$f(q)$$ $$=$$ $$q -\beta_{2} q^{2} + q^{4} -\beta_{1} q^{5} + q^{9} +O(q^{10})$$ $$q -\beta_{2} q^{2} + q^{4} -\beta_{1} q^{5} + q^{9} + ( \beta_{1} + \beta_{3} ) q^{10} -\beta_{3} q^{11} - q^{16} - q^{17} -\beta_{2} q^{18} -\beta_{1} q^{20} + ( \beta_{1} - \beta_{3} ) q^{22} + \beta_{1} q^{23} + ( 1 + \beta_{2} ) q^{25} + \beta_{3} q^{29} + \beta_{3} q^{31} + \beta_{2} q^{32} + \beta_{2} q^{34} + q^{36} + \beta_{1} q^{41} -\beta_{3} q^{44} -\beta_{1} q^{45} + ( -\beta_{1} - \beta_{3} ) q^{46} - q^{47} + q^{49} + ( -2 - \beta_{2} ) q^{50} + \beta_{2} q^{55} + ( -\beta_{1} + \beta_{3} ) q^{58} + \beta_{2} q^{59} + ( -\beta_{1} + \beta_{3} ) q^{62} - q^{64} - q^{68} -\beta_{3} q^{73} + \beta_{1} q^{80} + q^{81} + ( -\beta_{1} - \beta_{3} ) q^{82} + \beta_{1} q^{85} + ( \beta_{1} + \beta_{3} ) q^{90} + \beta_{1} q^{92} + \beta_{2} q^{94} -\beta_{2} q^{98} -\beta_{3} q^{99} +O(q^{100})$$ $$\operatorname{Tr}(f)(q)$$ $$=$$ $$4q + 4q^{4} + 4q^{9} + O(q^{10})$$ $$4q + 4q^{4} + 4q^{9} - 4q^{16} - 4q^{17} + 4q^{25} + 4q^{36} - 4q^{47} + 4q^{49} - 8q^{50} - 4q^{64} - 4q^{68} + 4q^{81} + O(q^{100})$$

Character values

We give the values of $$\chi$$ on generators for $$\left(\mathbb{Z}/799\mathbb{Z}\right)^\times$$.

 $$n$$ $$52$$ $$377$$ $$\chi(n)$$ $$-1$$ $$-1$$

Embeddings

For each embedding $$\iota_m$$ of the coefficient field, the values $$\iota_m(a_n)$$ are shown below.

For more information on an embedded modular form you can click on its label.

Label $$\iota_m(\nu)$$ $$a_{2}$$ $$a_{3}$$ $$a_{4}$$ $$a_{5}$$ $$a_{6}$$ $$a_{7}$$ $$a_{8}$$ $$a_{9}$$ $$a_{10}$$
798.1
 1.84776 −1.84776 0.765367 −0.765367
−1.41421 0 1.00000 −1.84776 0 0 0 1.00000 2.61313
798.2 −1.41421 0 1.00000 1.84776 0 0 0 1.00000 −2.61313
798.3 1.41421 0 1.00000 −0.765367 0 0 0 1.00000 −1.08239
798.4 1.41421 0 1.00000 0.765367 0 0 0 1.00000 1.08239
 $$n$$: e.g. 2-40 or 990-1000 Significant digits: Format: Complex embeddings Normalized embeddings Satake parameters Satake angles

Inner twists

Char Parity Ord Mult Type
1.a even 1 1 trivial
799.c odd 2 1 CM by $$\Q(\sqrt{-799})$$
17.b even 2 1 inner
47.b odd 2 1 inner

Twists

By twisting character orbit
Char Parity Ord Mult Type Twist Min Dim
1.a even 1 1 trivial 799.1.c.c 4
17.b even 2 1 inner 799.1.c.c 4
47.b odd 2 1 inner 799.1.c.c 4
799.c odd 2 1 CM 799.1.c.c 4

By twisted newform orbit
Twist Min Dim Char Parity Ord Mult Type
799.1.c.c 4 1.a even 1 1 trivial
799.1.c.c 4 17.b even 2 1 inner
799.1.c.c 4 47.b odd 2 1 inner
799.1.c.c 4 799.c odd 2 1 CM

Hecke kernels

This newform subspace can be constructed as the kernel of the linear operator $$T_{2}^{2} - 2$$ acting on $$S_{1}^{\mathrm{new}}(799, [\chi])$$.

Hecke characteristic polynomials

$p$ $F_p(T)$
$2$ $$( -2 + T^{2} )^{2}$$
$3$ $$T^{4}$$
$5$ $$2 - 4 T^{2} + T^{4}$$
$7$ $$T^{4}$$
$11$ $$2 - 4 T^{2} + T^{4}$$
$13$ $$T^{4}$$
$17$ $$( 1 + T )^{4}$$
$19$ $$T^{4}$$
$23$ $$2 - 4 T^{2} + T^{4}$$
$29$ $$2 - 4 T^{2} + T^{4}$$
$31$ $$2 - 4 T^{2} + T^{4}$$
$37$ $$T^{4}$$
$41$ $$2 - 4 T^{2} + T^{4}$$
$43$ $$T^{4}$$
$47$ $$( 1 + T )^{4}$$
$53$ $$T^{4}$$
$59$ $$( -2 + T^{2} )^{2}$$
$61$ $$T^{4}$$
$67$ $$T^{4}$$
$71$ $$T^{4}$$
$73$ $$2 - 4 T^{2} + T^{4}$$
$79$ $$T^{4}$$
$83$ $$T^{4}$$
$89$ $$T^{4}$$
$97$ $$T^{4}$$


text:
# Text object alpha BGE python for fade in/out 2.79

I am working on a "display name" with a text object added from a inactive layer to the current scene.

I startet just changing the visibility, then i wanted a "scaling visibility". For that (since the base class of the text object is game object) i try texObj.meshes[0].material[0].alpha but found that there is no meshes.

Then i put a plane.color =[0,0,0] behind the text and meet the colors (text.color=[amount,amount,amount]), amount = amount + or - 0.02 between 0.0 and 1 to slowly make a "scaling visibility" of the text, But this requires the plane as background of the text which i want to not use if there is a way to do it without a background.

Also i have google "bge python text to mesh" trying to found a way to convert the text to mesh so i could add the text object then edit,remesh,show,hide, endObject but only found the bpy reference which not work in bge runtime.

And of course a dont want to convert the text to a mesh (Alt+C) since i will unable to change the text.

Animate the alpha of GameObject.color

Tested using gamelogic module template, with a mouse sensor on text object. Clicking 10 times makes the text object "fade away".

def main(cont):
own = cont.owner
# color vector xyzw  ~ rgba
own.color.w -= 0.1
own.text = str(own.color)

• LOL I did not think about the color alpha, now i can change the color too, thank you it work perfectly. – Strapicarus Nov 18 '17 at 17:45

Assuming you already know about the limitations of text objects in the game engine: pixelated text, no materials, does not look the same in game as the real text object, depth buffer issues, etc. and still want to use a text object batFINGER's answer is pretty much what you want to do object.color = [r,g,b,a].

However I would recommend you use the Font Drawing module blf.

The example on the documentation page is almost all you need to know to start writing text using blf. Here is a very similar example.

import bge, bgl, blf

def init():
"""init function - runs once"""
global scene
# create a new font object from external ttf file and store the font indice - to use later

# set the font drawing routine to run every frame
scene = bge.logic.getCurrentScene()
scene.post_draw = [write]

def write():
"""write on screen"""
width = bge.render.getWindowWidth()
height = bge.render.getWindowHeight()

# OpenGL setup
bgl.glMatrixMode(bgl.GL_PROJECTION)
bgl.gluOrtho2D(0, width, 0, height)
bgl.glMatrixMode(bgl.GL_MODELVIEW)

# BLF drawing routine
font_id = bge.logic.font_id
blf.position(font_id, 10, (height - 45), 0)
blf.size(font_id, 40, 72)
bgl.glColor4f(.02,.2,.6,.8)
blf.draw(font_id, 'Hello BGE!')

Some key things to note from that script.

• expandPath('//Roboto-Regular.ttf') is looking in the same directory as the blend for that font file. Replace with your own.
• The position is in the top left with 10px margin-left. The position's origin is bottom left, so height-45 brings the text to the top minus the height of the text.
• bgl.glColor4f this is how you set the color with an alpha value (r,g,b,a) all 0 through 1 values. (I have it to a semi-transparent blue color)
• blf.draw what actually draws the text! to make it more useful use a string type game property.
• This is what I needed from the beginning?... it's a case study, thank you!. This is way better if can get it work as i want, but i done some test and was unable to change the text, found that the color need to be in the string and i couldn't "make copies", etc. the only thing that worked was shadow fade in/out , i will work on it when i have some time. For the moment object.color = [r,g,b,a] is my answer. – Strapicarus Nov 19 '17 at 7:23


text:
1617-257/TUT-R-6

On 10/20/16, we discussed how one can calculate the derivative of the inverse of the map $f: (0,1/2) \times (0, \pi/4) \to U \subset \mathbb R^2$ where $f(r, \theta) := (r \cos \theta, r \sin \theta)$:
Method 1. Find $f^{-1}$ explicitly and differentiate it.


text:
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# 710 (Q50, V35)......Thank God!!! got the monkey off my back

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710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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28 Jul 2008, 12:08
I took the GMAT yesterday (on 27th July) but could not write because I was partying hard.

I have been a part of GMAT club for more than a year. It has been a great learning experience as a member of GMAT club. Thanks to GMAT club, which has definitely contributed to my score.

This is not a stellar score. But I am no genius so happy with whatever it is. I could do this much with my little son (7 months old) around. I could be happier if it were 80-80 split as I have heard that adcoms prefer 80-80 split.

Exam day:
I got the exam scheduled at 9:00 AM on Sunday, July 27th. I was not feeling well (having a fever) as I got caught by viral fever three days back. So I could not study much during final days. The previous night to the G-day, I went to bed early (9 pm) and got up at 6:15 am. Got ready and had a light breakfast and kept a bottle of orange juice and a banana for the exam center.
I reached the exam center quite early and started the test at 8:45am.
Two essays - first (argument) went smooth and the second one went ok...

Took break, went to rest room, splashed some water on face...had some juice and ate half banana to get some energy...

Then came the Quants...first question...was a long PS it took bit long (more than 2 mins) to solve. But I was not in hurry. My strategy was to make first ten questions RIGHT...believe me whatever the GMAT scoring algorithm may be.. but first 10 questions matter a lot for your score.....I have tried this on GMAT Focus and GMAT prep and scored well whenever I did first ten questions correct.
I was not having much problem with the speed. I was very much on the scheduled but last two questions I had 1.5 mins so had to guess the last one. Overall, I was not unhappy with the quants.

After quants, took a break and repeated the same thing as I did in the first break....

Then came the beast...Verbal portion...started with the SC...The same strategy I followed in verbal also - try to make first 10 questions right. Few questions later...RC came... which drove me crazy...I read it twice got nothing substantial out of it...it dragged my confidence down...but never mind...I was ready for the worst..then came a few SCs and CRs..they went smooth...again came a RC, which was worse than the previous..oh my God..I thought I would not get more than 30....these ate up lot of time..and ultimately I had 9 questions and 13 mins left. I knew that I had to guess a few of them...I rushed...and guessed last 3 questions...and left everything to God...Thank God no bold face appeared..I hate them to the core.

After I answered the survey questions..not interestingly...I clicked on the report score...It's started processing...took a few seconds.. I closed up my eyes....and when I opened up eyes....it was 710....oh my GOD...big thanks...I crossed the 700 barrier...I was quite happy....though it may be a mediocre score for some..but I was not tragetting something around 750 or more...
So that's the story of the G-day...

My preparation:
I started serious preparation from Mar 2007 onwards, prepared for 3-4 months. I couldn't continue because of personal reasons. I came back to India in Oct' 2007. My son was born in Dec, 2007. So could not study for 3-4 months....Then I started preparing seriously again from end of Mar 2008 and took GMAT on 27th July, after 4 months of serious preparation.

Quants: I am from engineering back ground so have good maths skills. GMAT club challenges is a good source to learn the tricks and concepts. Last 50 questions from OG11 are good to practice on.

Verbal:
SC: MGMAT SCs guide, Spidey's Notes. Manhattangmatforums. I would strongly recommend 800BOB's (at testmagic forums) explanations to SCs. He is the master of SCs. I used to score good on SCs in practice test (accuracy - 80-85 %)..
CR: I did GMAT CRs Bible from Powerscore and offcourse OGs. I was neither extremely bad nor good at CRs.
RC: I had to struggle with RCs. I hate RCs.

Study materials:
OG11, OG10, Official Quants Guide, Offcial Verbal Guide: They are must have books. I studied them extensively...
GMAT focus: Not worth, I would not recomment them...
GMAT Club Challenges: (http://www.gmatclub.com/wiki/tests)Must buy....they are worth every cent you spend on them...
MGMAT SC guide: Must have for SCs
Kaplan 800: I did it but did not like.....Kaplan is not close to GMAT pattern.
Princeton Review: Good to start with but not good for advanced preparation.
GMAT CR bible from PowerScore: Very good book to learn CRs from.
LSAT book: I bought it but didn't study much.

CAT preparation Results:
GMAT prep - I : 670 (Q49, V32) 8th May 08
GMAT prep - II : 690 (Q49, V34) 25th Jun 08
Power Prep -I: 690 (Q47, V37)......not a good predictor of your performance....Qaunts is ridiculous..
GMAT Prep Reset -I : 730 (q49, V40): 6th July
GMAT Prep Reset -II : 620 (q49, V25): 22nd July............off day....but it drove me crazy..
GMAT prep Reinstalled -I: 710(Q51, V35) 24th July....bit skewed..but this was the peak of my quants...thank God it came at right time..
GMAT prep Reinstalled -II: 700(Q51, V32) 25th July..so this..

In MGMAT CATS I scored from 670 to 730....
I took PR CAT too...but found not good for GMAT preparation...They are not GMAT like.

Real GMAT: 710 (Q50, V35) 27th July

GMAT Prep tests are the best and the most accurate predictor of your performance. I think the MGMAT CATs are also good. Their Quants is lengthy and tough but good for practice. Verbal is also good. Actually nothing is close to GMAT pattern as far as verbal is concerned. Verbal questions are very difficult to mimic with GMAT flavor. Kaplan is ridiculuosly tough making no sense. GMAT is not all about solving tough questions, it's about learning the tricks to solve GMAT type problems. Only pratice can make you learn the GMAT pattern.

My success formula for the last SEVEN days(this worked for me)
Better to take a week off from your work and sleep at least 8 hrs every day during the last week.

Revise all Maths formulae and Verbal notes on the very first day.

For the next five days...do ONLY GMAT prep tests and their Questions....to get into rhythm for the real test...take a test (only GMAT prep) daily for 5 days....you will get repeats...don't worry...you know how much you have really scored... This will give the variety and degree of challenge you are going to face in the real TEST.

Seventh day....I would not recommend to take the practice test a day before your G-day. Don't stress too much, Relax,,,,go to religious places....to be calm and get blessings from Almighty..leave it to God and get a proper sleep..

G-day.....smash it...

Last but not least...thanks all of you whoever contributed to my preparation....GMAT Clubbers roccccccccckkkkkkkkkkk...

That's all for now....please feel free to ask about any help...If I can be of any..

My sincere thanks to TimeSquareDesi, jallenmorris, fresinha12, walker, Tarmac,abhaypratapsingh, dushver, barfer, x-ALI-x, mbawaters for your good words.

Last edited by vshaunak@gmail.com on 04 Feb 2009, 11:48, edited 8 times in total.
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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28 Jul 2008, 12:20
Congrats! Your quant scores on your practice exams are killer!

Can you offer any advice at all about quant?

Best of luck on apps,
- tsd
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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28 Jul 2008, 12:31
Great score! Wow, Q50 is unbelievable. Don't worry too much about the 80/80 Split. I've been asking about that a lot in the last few days and what i've gathered is it's nice to have, but certainly no hard rule that it's necessary. Your 710 stacks up the same as any other score in the low 700s. I think there is truly very little difference between 700 - 740.
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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28 Jul 2008, 12:51
awesome score! i am soooo happy for you...

good luck and stick around..at least i need your help for Q...
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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28 Jul 2008, 13:12
Expert's post
Congrats!!! It is excellent news

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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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28 Jul 2008, 15:03
Great job on the score!

One note though, I don't agree with taking so much time off work. It's not necessary. Save your days for a real vacation and interviews.

vshaunak@gmail.com wrote:

My success formula for the last SEVEN days(this worked for me)
Better to take a week off from your work and sleep at least 8 hrs every day during the last week.

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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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28 Jul 2008, 22:27
Any suggestions for quant ? I am stuck with 34-38 range , i have given 6 CATS so far.

thnks,
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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28 Jul 2008, 23:29
Congrats mate, great score. I like your last seven days strategy.
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29 Jul 2008, 22:36
Super!!!! Excellent result! Sexy Q-score!!!
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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30 Jul 2008, 10:31
TimeSquareDesi wrote:
Congrats! Your quant scores on your practice exams are killer!

Can you offer any advice at all about quant?

Best of luck on apps,
- tsd

Thanks for wishes.

Please let me know what specific topics you need advice on?
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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30 Jul 2008, 10:35
I'm just wondering which resources you used and went through in order to gain confidence in Quant. Which books did you use, any online sites/resources?

- tsd
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30 Jul 2008, 10:46
TimeSquareDesi wrote:
I'm just wondering which resources you used and went through in order to gain confidence in Quant. Which books did you use, any online sites/resources?

- tsd

I used OG 11 and OG Quants Guide (green one).
GMAT club Challenges are must....they are worth every penny...they are bit harder than GMAT and teach you to handle the trap in DS questions.

Actually beating GMAT quants does require you to be skilled at not to be caught in the traps. GMAT writers are good at creating traps. I suggest - read the question very carefully at least twice and before clicking the answer read once more to make sure you have answered what was desired.
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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30 Jul 2008, 10:52
1
KUDOS
Tarmac wrote:
Great job on the score!

One note though, I don't agree with taking so much time off work. It's not necessary. Save your days for a real vacation and interviews.

vshaunak@gmail.com wrote:

My success formula for the last SEVEN days(this worked for me)
Better to take a week off from your work and sleep at least 8 hrs every day during the last week.

Thanks.
Actually I had a luxury to take a week off....but not many have ...
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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30 Jul 2008, 11:32
Congrats, great stuff!
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Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back [#permalink]

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31 Jul 2008, 14:36
Nice score! congratulations you are ova the hump!
Re: 710 (Q50, V35)......Thank God!!! got the monkey off my back   [#permalink] 31 Jul 2008, 14:36
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