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view main/comm/quantiz.m @ 0:6b33357c7561 octave-forge
Initial revision
author | pkienzle |
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date | Wed, 10 Oct 2001 19:54:49 +0000 |
parents | |
children | 039e2a73aa8d |
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## 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 2 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, write to the Free Software ## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA ## 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). ## ## [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). ## ## [qidx, q, d] = quantiz(...) ## Compute distortion as mean squared distance of x from the ## corresponding table positions. Note that an equally valid ## definition of distortion is the distance from the codebook ## values. 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) warning("distortion is relative to table instead of codes"); table = [table(1) ; table(:) ]; d = sumsq (x(:) - table(qidx+1)) / length(x); endif endfunction