DST2e(x)

function f = DST2e(x)
%Calculation of DST2e using DCT2e.
%Reference Z. Wang, A fast algorithm for the discrete sine transform implemented
% by the fast cosine transform, IEEE Trans. Acoust., Speech, Signal
% Processing, vol. ASSP-30, pp. 814-815, 1982.

N=length(x);

s(1:2:N,1)=1;
s(2:2:N,1)=-1;

x=x.*s;
f=DCT2e(x);
f=flipud(f);