function x = myexprnd(lambda,r,c)
%    x = myexprnd(lambda,r,c)
% 
%    Return an R by C matrix of random samples from the exponential
%    distribution with parameter LAMBDA, which must be a scalar or of
%    size R by C.
%
%    Values of LAMBDA must be greater than zero.  
%
%    Example: 
%    To view the PDF of a single exponential random variable of 
%    mean 1 and standard deviation 1, use the command ...
%      n=10000; x=myexprnd(1,1,n); hist(x,n/100); avg_x = sum(x)/n
%
%    Reference:   http://en.wikipedia.org/wiki/Exponential_distribution

 if nargin < 2, [r,c] = size (lambda); end
 if any(size(lambda) - [r,c]) & length(lambda) ~= 1
    size_of_lambda = size(lambda)
    r
    c
    error(' myexprnd: LAMBDA must be a scalar or of size R by C')
 end
 if any(lambda<=0) || any(lambda==Inf)
    error(' myexprnd: LAMBDA must be greater than zero')
 end
 if length(lambda) == 1
    lambda = lambda * ones(r,c);
 end

 x = -log( 1 - rand(r,c) ) ./ lambda;

% --------------------------------------------------------------  MYEXPRND