[PD] a little pitchshifter

[Charles Henry]

> (2/N)*[1+sum{ j=1:N/2 ; cos(pi*t*fs*j) }

I left out an N and a factor of 2.  That should say

(2/N)*[1+sum{ j=1:N/2 ; cos(2*pi*t*fs*j/N) }