From bug-request at octave dot org Tue Mar 21 12:03:02 2006
Subject: Re: try catch block not working after error in FORTRAN code in	2.9.4
From: David Bateman <David dot Bateman at motorola dot com>
To: Wolfgang Lehrach <s0239540 at sms dot ed dot ac dot uk>
Cc: bug at octave dot org
Date: Tue, 21 Mar 2006 18:58:46 +0100

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Wolfgang Lehrach wrote:

>Hi - according to http://mathworld.wolfram.com/GammaFunction.html, gamma
>for negative non-integers is defined.  matlab and octave will both
>evaluate gamma(-0.5) to the same value (-3.5449).  gammaln will
>currently not work for negative input values for both, despite being
>sometimes defined (gamma(-1.5) = 2.3633, so gammaln should be ok in
>theory as well).  
>
>Maybe replace:
> else if (x <= 0 || xisinf (x))
>with:
> else if ((x <= 0) && floor(x) == x) || xisinf (x))
>in the check below?
>
>or whatever the best way to check a value being an integer would be...
>
>Thanks,
>Wolfgang
>
>PS  David, sorry for duplicate.
>  
>
Ok, this patch is going to drive me crazy.... Then what about this...

D.

-- 
David Bateman                                David dot Bateman at motorola dot com
Motorola Labs - Paris                        +33 1 69 35 48 04 (Ph) 
Parc Les Algorithmes, Commune de St Aubin    +33 6 72 01 06 33 (Mob) 
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*** ./liboctave/lo-specfun.cc.orig3	2005-04-26 21:24:29.000000000 +0200
--- ./liboctave/lo-specfun.cc	2006-03-21 18:57:01.884052840 +0100
***************
*** 37,42 ****
--- 37,43 ----
  #include "lo-ieee.h"
  #include "lo-specfun.h"
  #include "mx-inlines.cc"
+ #include "lo-mappers.h"
  
  #ifndef M_PI
  #define M_PI 3.14159265358979323846
***************
*** 160,166 ****
  xgamma (double x)
  {
    double result;
!   F77_XFCN (xdgamma, XDGAMMA, (x, result));
    return result;
  }
  
--- 161,173 ----
  xgamma (double x)
  {
    double result;
! 
!   if (xisnan (x))
!     result = x;
!   else if ((x <= 0 && D_NINT (x) == x) || xisinf (x))
!     result = octave_Inf;
!   else
!     F77_XFCN (xdgamma, XDGAMMA, (x, result));
    return result;
  }
  
***************
*** 170,180 ****
    double result;
    double sgngam;
  
!   if (x < 0)
!     (*current_liboctave_error_handler)
!       ("xlgamma: argument must be nonnegative");
! 
!   F77_XFCN (dlgams, DLGAMS, (x, result, sgngam));
  
    return result;
  }
--- 177,188 ----
    double result;
    double sgngam;
  
!   if (xisnan (x))
!     result = x;
!   else if (x <= 0 || xisinf (x))
!     result = octave_Inf;
!   else
!     F77_XFCN (dlgams, DLGAMS, (x, result, sgngam));
  
    return result;
  }

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