fconv.m

function [y] = fconv(x, h)
%FCONV Fast Convolution
%   [y] = FCONV(x, h) convolves x and h, and normalizes the output
%         to +-1.
%
%      x = input vector
%      h = input vector
%
%      See also CONV
%
%   NOTES:
%
%   1) I have a short article explaining what a convolution is.  It
%      is available at http://stevem.us/fconv.html.
%
%
%Version 1.0
%Coded by: Stephen G. McGovern, 2003-2004.

Ly = length(x) + length(h) - 1; %
Ly2 = pow2(nextpow2(Ly));       % Find smallest power of 2 that is > Ly
X = fft(x, Ly2);                % Fast Fourier transform
H = fft(h, Ly2);                % Fast Fourier transform
Y = X .* H;                     %
y = real(ifft(Y, Ly2));         % Inverse fast Fourier transform
y = y(1:1:Ly);                  % Take just the first N elements
%y=y/max(abs(y));               % Normalize the output (commented by SOUND.TOOLS, we don't need this normalization)