[Octave-cvsupdate] SF.net SVN: octave:[9558] trunk/octave-forge/main/specfun

[<car...@us...>]

Revision: 9558
          http://octave.svn.sourceforge.net/octave/?rev=9558&view=rev
Author:   carandraug
Date:     2012-01-23 11:19:04 +0000 (Mon, 23 Jan 2012)
Log Message:
-----------
lfactorial: new function to specfun package by Akos Marton <mak...@gm...>

Modified Paths:
--------------
    trunk/octave-forge/main/specfun/NEWS

Added Paths:
-----------
    trunk/octave-forge/main/specfun/inst/lfactorial.m

Modified: trunk/octave-forge/main/specfun/NEWS
===================================================================
--- trunk/octave-forge/main/specfun/NEWS	2012-01-23 11:17:56 UTC (rev 9557)
+++ trunk/octave-forge/main/specfun/NEWS	2012-01-23 11:19:04 UTC (rev 9558)
@@ -3,7 +3,7 @@
 
  ** The following functions are new:
 
-      big_factorial
+      big_factorial  lfactorial
 
 
 Summary of important user-visible changes for specfun 1.1.0:

Added: trunk/octave-forge/main/specfun/inst/lfactorial.m
===================================================================
--- trunk/octave-forge/main/specfun/inst/lfactorial.m	                        (rev 0)
+++ trunk/octave-forge/main/specfun/inst/lfactorial.m	2012-01-23 11:19:04 UTC (rev 9558)
@@ -0,0 +1,36 @@
+## Copyright (C) 2012 Akos Marton <mak...@gm...>
+##
+## This program is free software; you can redistribute it and/or modify it under
+## the terms of the GNU General Public License as published by the Free Software
+## Foundation; either version 3 of the License, or (at your option) any later
+## version.
+##
+## This program is distributed in the hope that it will be useful, but WITHOUT
+## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+## details.
+##
+## You should have received a copy of the GNU General Public License along with
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} lfactorial (@var{n})
+## Return the factorial of @var{n} where @var{n} is a positive integer.
+##
+## Return value approximated on natural logarithmic scale in order to
+## calculate the factorial of large numbers. For
+## vector or matrix arguments, return the lfactorial of each element in the
+## array.  For non-integers see the generalized factorial function
+## @code{lgamma}.
+##
+## @seealso{lgamma, big_factorial}
+## @end deftypefn
+
+function ans = lfactorial (n)
+  if (nargin != 1)
+    print_usage ();
+  elseif (any (n(:) < 0 | n(:) != round (n(:))))
+    error ("factorial: N must all be nonnegative integers");
+  endif
+  ans = lgamma (n+1);
+endfunction

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