5261 libm should stop using synonyms.h
5298 fabs is 0-sized, confuses dis(1) and others
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Approved by: Gordon Ross <gwr@nexenta.com>

          --- old/usr/src/lib/libm/common/Q/atanhl.c
          +++ new/usr/src/lib/libm/common/Q/atanhl.c

   1    1  /*
   2    2   * CDDL HEADER START
   3    3   *
   4    4   * The contents of this file are subject to the terms of the
   5    5   * Common Development and Distribution License (the "License").
   6    6   * You may not use this file except in compliance with the License.
   7    7   *
   8    8   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9    9   * or http://www.opensolaris.org/os/licensing.
  10   10   * See the License for the specific language governing permissions
  11   11   * and limitations under the License.
  12   12   *
  13   13   * When distributing Covered Code, include this CDDL HEADER in each
  14   14   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15   15   * If applicable, add the following below this CDDL HEADER, with the
  16   16   * fields enclosed by brackets "[]" replaced with your own identifying
  17   17   * information: Portions Copyright [yyyy] [name of copyright owner]
  18   18   *
  19   19   * CDDL HEADER END

  20   20   */
  21   21  
  22   22  /*
  23   23   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24   24   */
  25   25  /*
  26   26   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27   27   * Use is subject to license terms.
  28   28   */
  29   29  
  30      -#pragma weak atanhl = __atanhl
       30 +#pragma weak __atanhl = atanhl
  31   31  
  32   32  #include "libm.h"
  33   33  
  34   34  /*
  35   35   *                   1              2x                           x
  36   36   *      atanhl(x) = --- * LOG(1 + -------) = 0.5 * log1pl(2 * --------)
  37   37   *                   2             1 - x                       1 - x
  38   38   * Note: to guarantee atanhl(-x) = -atanhl(x), we use
  39   39   *                  sign(x)              |x|
  40   40   *      atanhl(x) = ------- * log1pl(2*-------).

  41   41   *                     2               1 - |x|
  42   42   *
  43   43   * Special cases:
  44   44   *      atanhl(x) is NaN if |x| > 1 with signal;
  45   45   *      atanhl(NaN) is that NaN with no signal;
  46   46   *      atanhl(+-1) is +-INF with signal.
  47   47   *
  48   48   */
  49   49  
  50   50  static const long double zero = 0.0L, half = 0.5L, one = 1.0L;
  51   51  
  52   52  long double
  53   53  atanhl(long double x) {
  54   54          long double t;
  55   55  
  56   56          t = fabsl(x);
  57   57          if (t == one)
  58   58                  return (x / zero);
  59   59          t = t / (one - t);
  60   60          return (copysignl(half, x) * log1pl(t + t));
  61   61  }

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