Mercurial > hg > octave-lyh
annotate scripts/linear-algebra/null.m @ 11188:4cb1522e4d0f
Use function handle as input to cellfun,
rather than quoted function name or anonymous function wrapper.
| author | Rik <octave@nomad.inbox5.com> |
|---|---|
| date | Wed, 03 Nov 2010 17:20:56 -0700 |
| parents | a8ce6bdecce5 |
| children | eb9e0b597d61 |
| rev | line source |
|---|---|
| 7017 | 1 ## Copyright (C) 1994, 1995, 1996, 1997, 1999, 2000, 2003, 2005, 2006, |
| 8920 | 2 ## 2007, 2008 John W. Eaton |
| 2313 | 3 ## |
| 4 ## This file is part of Octave. | |
| 5 ## | |
| 6 ## Octave is free software; you can redistribute it and/or modify it | |
| 7 ## under the terms of the GNU General Public License as published by | |
| 7016 | 8 ## the Free Software Foundation; either version 3 of the License, or (at |
| 9 ## your option) any later version. | |
| 2313 | 10 ## |
| 11 ## Octave is distributed in the hope that it will be useful, but | |
| 12 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 14 ## General Public License for more details. | |
| 15 ## | |
| 16 ## You should have received a copy of the GNU General Public License | |
| 7016 | 17 ## along with Octave; see the file COPYING. If not, see |
| 18 ## <http://www.gnu.org/licenses/>. | |
| 1026 | 19 |
| 3372 | 20 ## -*- texinfo -*- |
| 21 ## @deftypefn {Function File} {} null (@var{a}, @var{tol}) | |
| 22 ## Return an orthonormal basis of the null space of @var{a}. | |
| 3426 | 23 ## |
| 2311 | 24 ## The dimension of the null space is taken as the number of singular |
| 3372 | 25 ## values of @var{a} not greater than @var{tol}. If the argument @var{tol} |
| 26 ## is missing, it is computed as | |
| 3426 | 27 ## |
| 3372 | 28 ## @example |
| 29 ## max (size (@var{a})) * max (svd (@var{a})) * eps | |
| 30 ## @end example | |
|
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a8ce6bdecce5
Improve documentation strings.
Rik <octave@nomad.inbox5.com>
parents:
10549
diff
changeset
|
31 ## @seealso{orth} |
| 3372 | 32 ## @end deftypefn |
| 557 | 33 |
| 5428 | 34 ## Author: KH <Kurt.Hornik@wu-wien.ac.at> |
| 2312 | 35 ## Created: 24 December 1993. |
| 36 ## Adapted-By: jwe | |
| 557 | 37 |
| 2312 | 38 function retval = null (A, tol) |
| 557 | 39 |
| 4371 | 40 if (isempty (A)) |
| 41 retval = []; | |
| 42 else | |
| 43 [U, S, V] = svd (A); | |
| 1065 | 44 |
| 4371 | 45 [rows, cols] = size (A); |
| 46 | |
| 47 [S_nr, S_nc] = size (S); | |
| 557 | 48 |
| 4371 | 49 if (S_nr == 1 || S_nc == 1) |
| 50 s = S(1); | |
| 51 else | |
| 52 s = diag (S); | |
| 53 endif | |
| 557 | 54 |
| 4371 | 55 if (nargin == 1) |
|
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Handle single precision eps values
David Bateman <dbateman@free.fr>
parents:
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changeset
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56 if (isa (A, "single")) |
| 10549 | 57 tol = max (size (A)) * s (1) * eps ("single"); |
|
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Handle single precision eps values
David Bateman <dbateman@free.fr>
parents:
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changeset
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58 else |
| 10549 | 59 tol = max (size (A)) * s (1) * eps; |
|
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df9519e9990c
Handle single precision eps values
David Bateman <dbateman@free.fr>
parents:
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diff
changeset
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60 endif |
| 4371 | 61 elseif (nargin != 2) |
| 6046 | 62 print_usage (); |
| 4371 | 63 endif |
| 557 | 64 |
| 4371 | 65 rank = sum (s > tol); |
| 66 | |
| 67 if (rank < cols) | |
| 68 retval = V (:, rank+1:cols); | |
|
7795
df9519e9990c
Handle single precision eps values
David Bateman <dbateman@free.fr>
parents:
7017
diff
changeset
|
69 if (isa (A, "single")) |
| 10549 | 70 retval(abs (retval) < eps ("single")) = 0; |
|
7795
df9519e9990c
Handle single precision eps values
David Bateman <dbateman@free.fr>
parents:
7017
diff
changeset
|
71 else |
| 10549 | 72 retval(abs (retval) < eps) = 0; |
|
7795
df9519e9990c
Handle single precision eps values
David Bateman <dbateman@free.fr>
parents:
7017
diff
changeset
|
73 endif |
| 4371 | 74 else |
| 75 retval = zeros (cols, 0); | |
| 76 endif | |
| 557 | 77 endif |
| 78 | |
| 79 endfunction |