%
% Optical Imaging and Spectroscopy
%
% David J. Brady
% Duke University
% www.opticalimaging.org
%
% 
function cc=circConv(a,b)
%circular convolution of equal size square matrices
if size(a)==size(b)
    leng=size(a,1);
    cc=zeros(leng);
    for i=1:leng
        xv=mod(i:(leng+i-1),leng)+1;
        for j=1:leng
            yv=mod(j:(leng+j-1),leng)+1;
            ar=a(xv,yv);
            cc(i,j)=sum(sum(ar.*b));
        end
    end
else
    error('matrices must be the same size')
end