function [gsrv1,gsrv2]=gngauss(m,sgma)
% [gsrv1,gsrv2]=gngauss(m,sgma)
% [gsrv1,gsrv2]=gngauss(sgma)
% [gsrv1,gsrv2]=gngauss
% GAGAUSS generates two independent Gaussian random variables with mean 
% m and standard deviation sgma.if one of the input arguments is missing
% it takes the mean as 0,and the standard deviation as the given parameter.
% If neither mean nor the variance is given ,it generates two standard
% Gaussian random variables.
if nargin==0, 
   m=0;sgma=1;
elseif nargin==1,
   sgma=m;m=0;
end;
u=rand;                          % a uniform random variable in (0,1)
z=sgma*(sqrt(2*log(1/(1-u))));   % a Reyleigh distributed random variable
u=rand;                          % another uniform random variable in (0,1)
gsrv1=m+z*cos(2*pi*u);
gsrv2=m+z*sin(2*pi*u);