function [f]=single_xcorr(w,gamma,amp,l,delta,time)
% MATLAB HELP:
%
% function [f]=single_xcorr(w,gamma,amp,l,delta,time)
%
% computes the cross-correlation by summing normal modes
%
% inputs:
%  w, frequencies in 1/s
%  gamma, damping rates in 1/s
%  amp, the amplitude for each mode
%  l, angular degrees
%  delta, the distance in radians
%  time, the time grid to compute on
% outputs:
%  f, the cross-correlation as a function of time
%
% see codes.ps or codes.pdf for more details
%
% aaron birch, may 21, 2002


%
% allocate space for the result
%
f=zeros(size(time));

%
% loop over modes, the factor 10^56 makes f of order 1, UGLY!
%
for (i=1:length(amp))
        a=10^56*(2*l(i)+1)/(4*pi)*AsympLegendreP(l(i),delta);
	f=f+amp(i)*a*cos(w(i)*time).*exp(-gamma(i)*time)/4/gamma(i);
end;