function grsv=gngauss(R,sgma)
if(nargin==0)
    R=0;
    sgma=1;
elseif(nargin==1)
    sgma=R;
    R=0;
end
U=rand;
z=sgma*(sqrt(2*log(1/(1-U))));
U=rand;
grsv(1)=R+z*cos(2*pi*U);
grsv(2)=R+z*sin(2*pi*U);