Mercurial > octave
annotate scripts/sparse/sprandn.m @ 11587:c792872f8942
all script files: untabify and strip trailing whitespace
| author | John W. Eaton <jwe@octave.org> |
|---|---|
| date | Thu, 20 Jan 2011 17:35:29 -0500 |
| parents | fd0a3ac60b0e |
| children | 14422cc782b2 |
| rev | line source |
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| 11523 | 1 ## Copyright (C) 2004-2011 Paul Kienzle |
| 5164 | 2 ## |
| 7016 | 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 | |
| 7 ## the Free Software Foundation; either version 3 of the License, or (at | |
| 8 ## your option) any later version. | |
| 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 | |
| 16 ## along with Octave; see the file COPYING. If not, see | |
| 17 ## <http://www.gnu.org/licenses/>. | |
| 18 ## | |
| 19 ## Original version by Paul Kienzle distributed as free software in the | |
| 20 ## public domain. | |
| 5164 | 21 |
| 22 ## -*- texinfo -*- | |
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23 ## @deftypefn {Function File} {} sprandn (@var{m}, @var{n}, @var{d}) |
| 5610 | 24 ## @deftypefnx {Function File} {} sprandn (@var{s}) |
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25 ## Generate a random sparse matrix. The size of the matrix will be |
| 5164 | 26 ## @var{m} by @var{n}, with a density of values given by @var{d}. |
| 27 ## @var{d} should be between 0 and 1. Values will be normally | |
| 28 ## distributed with mean of zero and variance 1. | |
| 29 ## | |
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30 ## Note: sometimes the actual density may be a bit smaller than @var{d}. |
| 5164 | 31 ## This is unlikely to happen for large really sparse matrices. |
| 32 ## | |
| 33 ## If called with a single matrix argument, a random sparse matrix is | |
| 34 ## generated wherever the matrix @var{S} is non-zero. | |
| 5642 | 35 ## @seealso{sprand} |
| 5164 | 36 ## @end deftypefn |
| 37 | |
| 38 ## Author: Paul Kienzle <pkienzle@users.sf.net> | |
| 39 | |
| 6498 | 40 function S = sprandn (m, n, d) |
| 41 if (nargin == 1) | |
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42 [i, j, v] = find (m); |
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43 [nr, nc] = size (m); |
| 6498 | 44 S = sparse (i, j, randn (size (v)), nr, nc); |
| 45 elseif (nargin == 3) | |
| 5164 | 46 mn = m*n; |
| 6498 | 47 k = round (d*mn); |
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48 idx = unique (fix (rand (min (k*1.01, k+10), 1) * mn)) + 1; |
| 6498 | 49 ## idx contains random numbers in [1,mn] |
| 50 ## generate 1% or 10 more random values than necessary in order to | |
| 51 ## reduce the probability that there are less than k distinct | |
| 52 ## values; maybe a better strategy could be used but I don't think | |
| 53 ## it's worth the price. | |
| 54 | |
| 55 ## actual number of entries in S | |
| 56 k = min (length (idx), k); | |
| 57 j = floor ((idx(1:k)-1)/m); | |
| 5164 | 58 i = idx(1:k) - j*m; |
| 6498 | 59 if (isempty (i)) |
| 60 S = sparse (m, n); | |
| 5164 | 61 else |
| 6498 | 62 S = sparse (i, j+1, randn (k, 1), m, n); |
| 5164 | 63 endif |
| 64 else | |
| 6046 | 65 print_usage (); |
| 5164 | 66 endif |
| 67 endfunction |