Mercurial > hg > octave-lyh
annotate scripts/general/ind2sub.m @ 9163:9cb0c21e97f7
Update section 17.4 (Sums and Products) of arith.txi
| author | Rik <rdrider0-list@yahoo.com> |
|---|---|
| date | Thu, 30 Apr 2009 16:13:18 -0700 |
| parents | 1bf0ce0930be |
| children | 16f53d29049f |
| rev | line source |
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| 7345 | 1 ## Copyright (C) 2001, 2003, 2004, 2005, 2006, 2007, 2008 Paul Kienzle |
| 4679 | 2 ## |
| 3 ## This file is part of Octave. | |
| 4 ## | |
| 5 ## Octave is free software; you can redistribute it and/or modify it | |
| 6 ## under the terms of the GNU General Public License as published by | |
| 7016 | 7 ## the Free Software Foundation; either version 3 of the License, or (at |
| 8 ## your option) any later version. | |
| 4679 | 9 ## |
| 10 ## Octave is distributed in the hope that it will be useful, but | |
| 11 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 ## General Public License for more details. | |
| 14 ## | |
| 15 ## You should have received a copy of the GNU General Public License | |
| 7016 | 16 ## along with Octave; see the file COPYING. If not, see |
| 17 ## <http://www.gnu.org/licenses/>. | |
| 4679 | 18 |
| 19 ## -*- texinfo -*- | |
| 4906 | 20 ## @deftypefn {Function File} {[@var{s1}, @var{s2}, @dots{}, @var{sN}] =} ind2sub (@var{dims}, @var{ind}) |
| 4679 | 21 ## Convert a linear index into subscripts. |
| 6631 | 22 ## |
| 23 ## The following example shows how to convert the linear index @code{8} | |
| 7345 | 24 ## in a 3-by-3 matrix into a subscript. The matrix is linearly indexed |
| 25 ## moving from one column to next, filling up all rows in each column. | |
| 6631 | 26 ## @example |
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27 ## @group |
| 6631 | 28 ## [r, c] = ind2sub ([3, 3], 8) |
| 29 ## @result{} r = 2 | |
| 30 ## c = 3 | |
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31 ## @end group |
| 6631 | 32 ## @end example |
| 5642 | 33 ## @seealso{sub2ind} |
| 4679 | 34 ## @end deftypefn |
| 35 | |
| 36 ## Author: Paul Kienzle <pkienzle@kienzle.powernet.co.uk> | |
| 37 ## Adapted-by: jwe | |
| 38 | |
| 39 function varargout = ind2sub (dims, ind) | |
| 40 | |
| 41 if (nargin == 2) | |
| 6050 | 42 if (isvector (dims) && all (round (dims) == dims)) |
| 43 if (isnumeric (ind) && all (round (ind) == ind)) | |
| 4679 | 44 ntot = prod (dims); |
| 6050 | 45 if (all (ind > 0 & ind <= ntot)) |
| 4679 | 46 nd = length (dims); |
| 47 if (nargout > 0) | |
| 48 vlen = nargout; | |
| 49 else | |
| 50 vlen = 1; | |
| 51 endif | |
| 52 if (nd > vlen); | |
| 53 dims(vlen) = prod (dims(vlen:nd)); | |
| 54 dims(vlen+1:nd) = []; | |
| 55 endif | |
| 56 nd = length (dims); | |
| 57 scale = [1; cumprod(dims(:))]; | |
| 58 for i = nd:-1:2 | |
| 59 k = (ind >= scale(i)); | |
| 60 r = ones (size (ind)); | |
| 61 t = zeros (size (ind)); | |
| 62 t(k) = floor ((ind(k) - 1) / scale(i)); | |
| 63 r(k) = t(k) + 1; | |
| 64 varargout{i} = r; | |
| 65 ind(k) -= t(k) * scale(i); | |
| 66 endfor | |
| 67 varargout{1} = ind; | |
| 68 for i = nd+1:vlen | |
| 69 varargout{i} = ones (size (ind)); | |
| 70 endfor | |
| 71 else | |
| 72 error ("ind2sub: index out of range"); | |
| 73 endif | |
| 74 else | |
| 75 error ("ind2sub: expecting integer-valued index argument"); | |
| 76 endif | |
| 77 else | |
| 5518 | 78 error ("ind2sub: expecting dims to be an integer vector"); |
| 4679 | 79 endif |
| 80 else | |
| 6046 | 81 print_usage (); |
| 4679 | 82 endif |
| 83 | |
| 84 | |
| 85 endfunction |