You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: spm_Bpdf.m
    path of file: ./repos/malini/Codes/deconvolution - model/spm8
    
    the code of the file until where you have to start completion: function f = spm_Bpdf(x,v,w)
% Probability Density Function (PDF) of Beta distribution
% FORMAT f = spm_Bpdf(x,v,w)
%
% x   - Beta variates (Beta has range [0,1])
% v   - Shape parameter (v>0)
% w   - Shape parameter (w>0)
% F   - PDF of Beta distribution with shape parameters [v,w] at points x
%__________________________________________________________________________
%
% spm_Bpdf implements the Probability Density Function for Beta distributions.
%
% Definition:
%--------------------------------------------------------------------------
% The PDF of the Beta distribution shape parameters v & w, defined
% for positive integer degrees of freedom v>0 & w>0, and for x in
% [0,1] is given by: (See Evans et al., Ch5)
%
%            x^(v-1) * (1-x)^(w-1)
%    f(x) = -----------------------
%                 beta(v,w)
%
% Variate relationships:
%--------------------------------------------------------------------------
% Many: See Evans et al., Ch5
%
% Algorithm:
%--------------------------------------------------------------------------
% Direct computation using logs and MATLAB's implementation of the log
% beta function (betaln).
%
% References:
%--------------------------------------------------------------------------

    
function f = spm_Bpdf(x,v,w)
% Probability Density Function (PDF) of Beta distribution
% FORMAT f = spm_Bpdf(x,v,w)
%
% x   - Beta variates (Beta has range [0,1])
% v   - Shape parameter (v>0)
% w   - Shape parameter (w>0)
% F   - PDF of Beta distribution with shape parameters [v,w] at points x
%__________________________________________________________________________
%
% spm_Bpdf implements the Probability Density Function for Beta distributions.
%
% Definition:
%--------------------------------------------------------------------------
% The PDF of the Beta distribution shape parameters v & w, defined
% for positive integer degrees of freedom v>0 & w>0, and for x in
% [0,1] is given by: (See Evans et al., Ch5)
%
%            x^(v-1) * (1-x)^(w-1)
%    f(x) = -----------------------
%                 beta(v,w)
%
% Variate relationships:
%--------------------------------------------------------------------------
% Many: See Evans et al., Ch5
%
% Algorithm:
%--------------------------------------------------------------------------
% Direct computation using logs and MATLAB's implementation of the log
% beta function (betaln).
%
% References:
%--------------------------------------------------------------------------
% Evans M, Hastings N, Peacock B (1993)
%       "Statistical Distributions"
%        2nd Ed. Wiley, New York
%
% Abramowitz M, Stegun IA, (1964)
%       "Handbook of Mathematical Functions"
%        US Government Printing Office
%
% Press WH, Teukolsky SA, Vetterling AT, Flannery BP (1992)
%       "Numerical Recipes in C"
%        Cambridge
%__________________________________________________________________________
% Copyright (C) 1999-2011 Wellcome Trust Centre for Neuroimaging

% Andrew Holmes
% $Id: spm_Bpdf.m 4182 2011-02-01 12:29:09Z guillaume $


%-Format arguments, note & check sizes
%--------------------------------------------------------------------------
if nargin<3, error('Insufficient arguments'), end