/usr/share/octave/packages/signal-1.3.2/kaiser.m is in octave-signal 1.3.2-1+b1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 | ## Copyright (C) 1995, 1996, 1997 Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at>
## Copyright (C) 2000 Paul Kienzle <pkienzle@users.sf.net>
##
## 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 3 of the License, 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 program; if not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {} kaiser (@var{m})
## @deftypefnx {Function File} {} kaiser (@var{m}, @var{beta})
##
## Return the filter coefficients of a Kaiser window of length @var{m}. The
## Fourier transform of the window has a stop-band attenuation that is derived
## from the parameter @var{beta}.
##
## For the definition of the Kaiser window, see A. V. Oppenheim &
## R. W. Schafer, "Discrete-Time Signal Processing".
##
## The continuous version of width m centered about x=0 is:
##
## @example
## @group
## besseli(0, beta * sqrt(1-(2*x/m).^2))
## k(x) = -------------------------------------, m/2 <= x <= m/2
## besseli(0, beta)
## @end group
## @end example
##
## @seealso{kaiserord}
## @end deftypefn
function w = kaiser (m, beta = 0.5)
if (nargin < 1 || nargin > 2)
print_usage ();
elseif (! (isscalar (m) && (m == fix (m)) && (m > 0)))
error ("kaiser: M must be a positive integer");
elseif (! (isscalar (beta) && isreal (beta)))
error ("kaiser: BETA must be a real scalar");
endif
if (m == 1)
w = 1;
else
N = m - 1;
k = (0 : N)';
k = 2 * beta / N * sqrt (k .* (N - k));
w = besseli (0, k) / besseli (0, beta);
endif
endfunction
%!demo
%! % use demo("kaiserord");
%!assert (kaiser (1), 1)
%% Test input validation
%!error kaiser ()
%!error kaiser (0.5)
%!error kaiser (-1)
%!error kaiser (ones (1, 4))
%!error kaiser (1, 2, 3)
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