function gn = gradnorm(f)
%
% gradnorm: computes the norm of the gradient of f
% On input:
%     f: 2D array
% On output:
%     gn: norm of gradient at each point in f
% Call:
%     gn = gradnorm(f)
%

[px,py] = gradient(f);
gn = sqrt(px.*px+py.*py);
