Mercurial > octave-nkf
annotate scripts/specfun/betaln.m @ 20595:c1a6c31ac29a
eliminate more simple uses of error_state
* ov-classdef.cc: Eliminate simple uses of error_state.
| author | John W. Eaton <jwe@octave.org> |
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| date | Tue, 06 Oct 2015 00:20:02 -0400 |
| parents | 9fc020886ae9 |
| children |
| rev | line source |
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maint: Update copyright notices for 2015.
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1 ## Copyright (C) 1998-2015 Nicol N. Schraudolph |
| 5820 | 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. | |
| 5820 | 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/>. | |
| 5820 | 18 |
| 19 ## -*- texinfo -*- | |
| 20 ## @deftypefn {Mapping Function} {} betaln (@var{a}, @var{b}) | |
| 19132 | 21 ## Compute the natural logarithm of the Beta function for real inputs @var{a} |
| 22 ## and @var{b}. | |
| 23 ## | |
| 24 ## @code{betaln} is defined as | |
| 5820 | 25 ## @tex |
| 26 ## $$ | |
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betaln.m: Improve documentation string, particularly for Tex format.
Rik <octave@nomad.inbox5.com>
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27 ## {\rm betaln} (a, b) = \ln (B (a,b)) \equiv \ln ({\Gamma (a) \Gamma (b) \over \Gamma (a + b)}). |
| 5820 | 28 ## $$ |
| 29 ## @end tex | |
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30 ## @ifnottex |
| 5820 | 31 ## |
| 32 ## @example | |
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Rik <octave@nomad.inbox5.com>
parents:
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33 ## betaln (a, b) = log (beta (a, b)) |
| 5820 | 34 ## @end example |
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35 ## |
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36 ## @end ifnottex |
| 19132 | 37 ## and is calculated in a way to reduce the occurrence of underflow. |
| 38 ## | |
| 39 ## The Beta function can grow quite large and it is often more useful to work | |
| 40 ## with the logarithm of the output rather than the function directly. | |
| 41 ## @seealso{beta, betainc, betaincinv, gammaln} | |
| 5820 | 42 ## @end deftypefn |
| 43 | |
| 44 ## Author: Nicol N. Schraudolph <nic@idsia.ch> | |
| 45 ## Created: 06 Aug 1998 | |
| 46 ## Keywords: log beta special function | |
| 47 | |
| 48 function retval = betaln (a, b) | |
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betaln.m: Improve documentation string, particularly for Tex format.
Rik <octave@nomad.inbox5.com>
parents:
11587
diff
changeset
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49 |
| 5820 | 50 if (nargin != 2) |
| 6046 | 51 print_usage (); |
| 5820 | 52 endif |
| 53 | |
| 19132 | 54 if (! isreal (a) || ! isreal (b)) |
| 55 error ("betaln: A and B must be real"); | |
| 56 elseif (! size_equal (a, b) && numel (a) != 1 && numel (b) != 1) | |
| 57 error ("betaln: A and B must have consistent sizes"); | |
| 58 endif | |
| 59 | |
| 5820 | 60 retval = gammaln (a) + gammaln (b) - gammaln (a + b); |
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12659
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betaln.m: Improve documentation string, particularly for Tex format.
Rik <octave@nomad.inbox5.com>
parents:
11587
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changeset
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61 |
| 5820 | 62 endfunction |
| 63 | |
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Rik <octave@nomad.inbox5.com>
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64 |
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Rik <octave@nomad.inbox5.com>
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65 %!assert (betaln (3,4), log (beta (3,4)), eps) |
| 5820 | 66 |
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67 ## Test input validation |
| 19132 | 68 %!error betaln () |
| 69 %!error betaln (1) | |
| 70 %!error betaln (1,2,3) | |
| 71 %!error <A and B must be real> betaln (1i, 2) | |
| 72 %!error <A and B must be real> betaln (2, 1i) | |
| 73 %!error <A and B must have consistent sizes> betaln ([1 2], [1 2 3]) | |
| 74 %!error <A and B must have consistent sizes> betaln ([1 2 3], [1 2]) | |
| 75 %!error <A and B must have consistent sizes> betaln ([1 2 3], [1 2 3]') | |
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76 |