function w = taper
% Cosine bell tapering 
% Based on discussion in Time Sequence Analysis in Geophysics
% by E.R. Kanasewich.
% To be used with cross-correlation routine.  Works correctly
% for fraction < 0.1 .
%
% by D. Holmgren, June 20 94. holmgren@phobos.astro.uwo.ca

% input total length of taper, and fraction of which
% is to be a cosine bell...
n = input('Length of taper = ');
f = input('Fraction to taper = ');
m = f*n;
l = n - m;
w = ones(n,1);
% compute taper...
for i = 1:m
w(i) = 0.5 * (1 + cos(pi*(i+l)/m));
w(n-i+1) = 0.5 * (1 + cos(pi*(i-l)/m));
end