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 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 
  26 /*
  27  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  28  * Use is subject to license terms.
  29  */
  30 
  31 #pragma weak __asinhl = asinhl
  32 
  33 #include "libm.h"
  34 
  35 static const long double
  36         ln2 = 6.931471805599453094172321214581765680755e-0001L,
  37         one = 1.0L,
  38         big = 1.0e+20L,
  39         tiny = 1.0e-20L;
  40 
  41 long double
  42 asinhl(long double x)
  43 {
  44         long double t, w;
  45 
  46 #ifndef lint
  47         volatile long double dummy;
  48 #endif
  49 
  50         w = fabsl(x);
  51 
  52         if (isnanl(x))
  53                 return (x + x);         /* x is NaN */
  54 
  55         if (w < tiny) {
  56 #ifndef lint
  57                 dummy = x + big;        /* inexact if x != 0 */
  58 #endif
  59                 return (x);             /* tiny x */
  60         } else if (w < big) {
  61                 t = one / w;
  62                 return (copysignl(log1pl(w + w / (t + sqrtl(one + t * t))), x));
  63         } else {
  64                 return (copysignl(logl(w) + ln2, x));
  65         }
  66 }