fftconv Convolve two vectors using the FFT for computation. Y = fftconv(X, Y) Y = fftconv(X, Y, N) X, Y: Vectors Convolve two vectors using the FFT for computation. 'c' = fftconv (X, Y)' returns a vector of length equal to 'length(X) + length (Y) - 1'. If X and Y are the coefficient vectors of two polynomials, the returned value is the coefficient vector of the product polynomial.