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 __sinhl = sinhl
  32 
  33 #include "libm.h"
  34 #include "longdouble.h"
  35 
  36 /* BEGIN CSTYLED */
  37 /*
  38  * SINH(X)
  39  * RETURN THE HYPERBOLIC SINE OF X
  40  *
  41  * Method :
  42  *      1. reduce x to non-negative by SINH(-x) = - SINH(x).
  43  *      2.
  44  *
  45  *                                            EXPM1(x) + EXPM1(x)/(EXPM1(x)+1)
  46  *          0 <= x <= lnovft     : SINH(x) := --------------------------------
  47  *                                                            2
  48  *
  49  *     lnovft <= x <  INF  : SINH(x) := EXP(x-MEP1*ln2)*2**ME
  50  *
  51  * here
  52  *      lnovft          logarithm of the overflow threshold
  53  *                      = MEP1*ln2 chopped to machine precision.
  54  *      ME              maximum exponent
  55  *      MEP1            maximum exponent plus 1
  56  *
  57  * Special cases:
  58  *      SINH(x) is x if x is +INF, -INF, or NaN.
  59  *      only SINH(0)=0 is exact for finite argument.
  60  *
  61  */
  62 /* END CSTYLED */
  63 
  64 static const long double C[] = {
  65         0.5L,
  66         1.0L,
  67         1.135652340629414394879149e+04L,
  68         7.004447686242549087858985e-16L
  69 };
  70 
  71 #define half            C[0]
  72 #define one             C[1]
  73 #define lnovft          C[2]
  74 #define lnovlo          C[3]
  75 
  76 long double
  77 sinhl(long double x)
  78 {
  79         long double r, t;
  80 
  81         if (!finitel(x))
  82                 return (x + x);         /* x is INF or NaN */
  83 
  84         r = fabsl(x);
  85 
  86         if (r < lnovft) {
  87                 t = expm1l(r);
  88                 r = copysignl((t + t / (one + t)) * half, x);
  89         } else {
  90                 r = copysignl(expl((r - lnovft) - lnovlo), x);
  91                 r = scalbnl(r, 16383);
  92         }
  93 
  94         return (r);
  95 }