/usr/share/octave/packages/communications-1.1.1/quantiz.m is in octave-communications-common 1.1.1-1.
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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 | ## Copyright (C) 2001 Paul Kienzle
##
## 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} {@var{qidx} = } quantiz (@var{x}, @var{table})
## @deftypefnx {Function File} {[@var{qidx}, @var{q}] = } quantiz (@var{x}, @var{table}, @var{codes})
## @deftypefnx {Function File} {[ @var{qidx}, @var{q}, @var{d}] = } quantiz (@var{...})
##
## Quantization of an arbitrary signal relative to a paritioning.
##
## @table @code
## @item qidx = quantiz(x, table)
## Determine position of x in strictly monotonic table. The first
## interval, using index 0, corresponds to x <= table(1).
## Subsequent intervals are table(i-1) < x <= table(i).
##
## @item [qidx, q] = quantiz(x, table, codes)
## Associate each interval of the table with a code. Use codes(1)
## for x <= table(1) and codes(n+1) for table(n) < x <= table(n+1).
##
## @item [qidx, q, d] = quantiz(...)
## Compute distortion as mean squared distance of x from the
## corresponding quantization values.
## @end table
## @end deftypefn
function [qidx, q, d] = quantiz (x, table, codes)
if (nargin < 2 || nargin > 3)
usage("[qidx, q, d] = quantiz(x, table, codes)");
endif
qidx = length(table) - lookup(flipud(table(:)), x(:));
if (nargin > 2 && nargout > 1)
q = codes(qidx + 1);
endif
if (nargout > 2)
table = [table(1) ; table(:) ];
d = sumsq (x(:) - q(:)) / length(x);
endif
endfunction
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