[gnumeric] GAMMA: Use new gnm_gamma.

[Morten Welinder <mortenw src gnome org>]

commit 83d877986398e311a50c715e9d7c9a327244af8a
Author: Morten Welinder <terra gnome org>
Date:   Tue Aug 27 16:41:57 2013 -0400

    GAMMA: Use new gnm_gamma.

 plugins/fn-math/ChangeLog   |    4 ++++
 plugins/fn-math/functions.c |   15 +--------------
 2 files changed, 5 insertions(+), 14 deletions(-)
---
diff --git a/plugins/fn-math/ChangeLog b/plugins/fn-math/ChangeLog
index f4c5d50..0439299 100644
--- a/plugins/fn-math/ChangeLog
+++ b/plugins/fn-math/ChangeLog
@@ -1,3 +1,7 @@
+2013-08-27  Morten Welinder  <terra gnome org>
+
+       * functions.c (gnumeric_gamma): Use new gnm_gamma.
+
 2013-08-19  Morten Welinder <terra gnome org>
 
        * Release 1.12.5
diff --git a/plugins/fn-math/functions.c b/plugins/fn-math/functions.c
index afdb624..9caedb4 100644
--- a/plugins/fn-math/functions.c
+++ b/plugins/fn-math/functions.c
@@ -930,20 +930,7 @@ static GnmFuncHelp const help_gamma[] = {
 static GnmValue *
 gnumeric_gamma (GnmFuncEvalInfo *ei, GnmValue const * const *argv)
 {
-       gnm_float x = value_get_as_float (argv[0]);
-       gboolean x_is_integer = (x == gnm_floor (x));
-
-       if (x < 0 && x_is_integer)
-               return value_new_error_NUM (ei->pos);
-
-       if (x_is_integer)
-               return value_new_float (fact (x - 1));
-       else {
-               gnm_float res = gnm_exp (gnm_lgamma (x));
-               if (x < 0 && gnm_fmod (gnm_floor (-x), 2.0) == 0.0)
-                       res = 0 - res;
-               return value_new_float (res);
-       }
+       return value_new_float (gnm_gamma (value_get_as_float (argv[0])));
 }
 
 /***************************************************************************/