The Width of Gaussian Kernel

I have a MATLAB code for a gaussian kernel (Radial Basis Function):

dist = EuDist2(X{it},C{it},0);

sigma = mean(min(dist,[],2).^0.5)*2;

feaVec = exp(-dist/(2*sigma*sigma));

X and C are a known matrices;

What is the name of method used for the calculation of Sigma that way? is it a standard technique ?