% Routine for computing coherence function.
%
% Syntax: [gam,cxy] = cohrnce(x,y)
%
% by D. Holmgren, Aug 10 94. holmgren@phobos.astro.uwo.ca

function [gam,cxy] = cohrnce(x,y)
wx = zeros(2048,1); wy = wx;
nx = length(x); ny = length(y);
wx(1:nx) = x; wy(1:ny) = y;
X = fft(wx);
Y = fft(wy);
% shift and smooth spectra...
Xs = fftshift(X);
Ys = fftshift(Y);
Xsm = smooth(Xs);
Ysm = smooth(Ys);
% compute various power spectra...
Gxy = Xsm .* conj(Ysm);
Gxx = Xsm .* conj(Xsm);
Gyy = Ysm .* conj(Ysm);
% compute coherence...
gam = Gxy  ./ sqrt(Gxx .* Gyy);
cxy = gam .* conj(gam);