fftfilt Performs FFT-based FIR filtering using overlap-add method x: real|complex numbers - vector|matrix b: real|complex numbers - vector|matrix n: positive integer y = fftfilt(b,x) filters the data in vector x with the filter described by coefficient vector b. y = fftfilt(b,x,n) uses n to determine the length of the FFT. Ayush Baid