% circconv.m
% usage: Y = circconv(X,h)
% Performs circular convolution by h on X, the result has the same size as X.
% It is assumed that length(h) <= length(X).
% The result is the same as zero-padding h out to the length of X,
% and then computing the convolution X*h.
function Y=circconv(X,h)
Y = conv(X,h);
m = length(X);
n = length(Y);
Y(1:n-m) = Y(1:(n-m))+Y((m+1):n);
Y = Y(1:m);