%% energy.m
% usage: energy(X)
% X  is a vector or matrix
% compute the normalized energy of a vector or matrix
% the sum of squares is divided by the size of the signal

% S. Allen Broughton - 31 Oct 2010

function E = energy(X)
  Y = X(:); % convert to column vector
  E = real(Y'*Y/length(Y));