how use fftn and ifftn fourier transform

r=(fftn(matrix1) .* ifftn(matrix2)) ./ abs((fftn(matrix1) .* ifftn(matrix2))
r=ifftn(r)

then output is all of NaN in r matrix result, why happen this situation, how overcome this situation

thanks alot

[Adam]

I have no idea what you are trying to do in that expression, but just break it down into the 4 components and then the expressions combining each and look at them in the debugger. You will soon find where your NaNs are.