Mercurial > forge
comparison main/comm/quantiz.m @ 0:6b33357c7561 octave-forge
Initial revision
| author | pkienzle |
|---|---|
| date | Wed, 10 Oct 2001 19:54:49 +0000 |
| parents | |
| children | 039e2a73aa8d |
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| -1:000000000000 | 0:6b33357c7561 |
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| 1 ## Copyright (C) 2001 Paul Kienzle | |
| 2 ## | |
| 3 ## This program is free software; you can redistribute it and/or modify | |
| 4 ## it under the terms of the GNU General Public License as published by | |
| 5 ## the Free Software Foundation; either version 2 of the License, or | |
| 6 ## (at your option) any later version. | |
| 7 ## | |
| 8 ## This program is distributed in the hope that it will be useful, | |
| 9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 11 ## GNU General Public License for more details. | |
| 12 ## | |
| 13 ## You should have received a copy of the GNU General Public License | |
| 14 ## along with this program; if not, write to the Free Software | |
| 15 ## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 16 | |
| 17 ## qidx = quantiz(x, table) | |
| 18 ## Determine position of x in strictly monotonic table. The first | |
| 19 ## interval, using index 0, corresponds to x <= table(1). | |
| 20 ## Subsequent intervals are table(i-1) < x <= table(i). | |
| 21 ## | |
| 22 ## [qidx, q] = quantiz(x, table, codes) | |
| 23 ## Associate each interval of the table with a code. Use codes(1) | |
| 24 ## for x <= table(1) and codes(n+1) for table(n) < x <= table(n+1). | |
| 25 ## | |
| 26 ## [qidx, q, d] = quantiz(...) | |
| 27 ## Compute distortion as mean squared distance of x from the | |
| 28 ## corresponding table positions. Note that an equally valid | |
| 29 ## definition of distortion is the distance from the codebook | |
| 30 ## values. | |
| 31 function [qidx, q, d] = quantiz (x, table, codes) | |
| 32 if (nargin < 2 || nargin > 3) | |
| 33 usage("[qidx, q, d] = quantiz(x, table, codes)"); | |
| 34 endif | |
| 35 | |
| 36 qidx = length(table) - lookup(flipud(table(:)), x); | |
| 37 if (nargin > 2 && nargout > 1) | |
| 38 q = codes(qidx + 1); | |
| 39 endif | |
| 40 if (nargout > 2) | |
| 41 warning("distortion is relative to table instead of codes"); | |
| 42 table = [table(1) ; table(:) ]; | |
| 43 d = sumsq (x(:) - table(qidx+1)) / length(x); | |
| 44 endif | |
| 45 endfunction |