usr/src/lib/libm/common/C/gamma.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  23  */
  24 /*
  25  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  26  * Use is subject to license terms.
  27  */
  28
  29 #pragma weak __gamma = gamma
  30
  31 #include "libm.h"
  32
  33 extern int signgam;
  34
  35 double
  36 gamma(double x) {
  37         double  g;
  38
  39         if (!finite(x))
  40                 return (x * x);
  41
  42         g = rint(x);
  43         if (x == g && x <= 0.0) {
  44                 signgam = 1;
  45                 return (_SVID_libm_err(x, x, 41));
  46         }
  47
  48         g = __k_lgamma(x, &signgam);
  49         if (!finite(g))
  50             g = _SVID_libm_err(x, x, 40);
  51         return (g);
  52 }