function y = fast_dst(x)
% Perform a fast DST on a vector. Since Matlab does not have a DST function,
% this just uses the built in FFT function.
% parameter:
% x = input column vector
% returns:
%   y = the DST of x
%
n = length(x);
%
tmp = zeros(2*n + 2, 1);
tmp = -imag(fft([0; x; zeros(n+1,1)]));
y = tmp(2:n+1);
return