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## Copyright (C) 1995, 1996, 1997 Kurt Hornik
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2, or (at your option)
## any later version.
##
## This program is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this file. If not, write to the Free Software Foundation,
## 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
## usage: kaiser (n, beta)
##
## Returns the filter coefficients of the n-point Kaiser window with
## parameter beta.
##
## For the definition of the Kaiser window, see A. V. Oppenheim &
## R. W. Schafer, "Discrete-Time Signal Processing".
## Author: KH <Kurt.Hornik@ci.tuwien.ac.at>
## Description: Coefficients of the Kaiser window
function w = kaiser (n, beta)
if (nargin != 2)
usage ("kaiser (n, beta)");
endif
if !(is_scalar (n) && (n == round (n)) && (n > 0))
error ("kaiser: n has to be a positive integer");
endif
if !(is_scalar (beta) && (beta == real (beta)))
error ("kaiser: beta has to be a real scalar");
endif
if (n == 1)
w = 1;
else
m = n - 1;
k = (0 : m)';
k = 2 * beta / m * sqrt (k .* (m - k));
w = jybess (0, k * i) / jybess (0, beta * i);
endif
endfunction
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