usr/src/lib/libm/common/complex/cacosh.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 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 /*
  26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29
  30 #pragma weak __cacosh = cacosh
  31
  32 /* INDENT OFF */
  33 /*
  34  * dcomplex cacosh(dcomplex z);
  35  *      cacosh z = +-i cacos z .
  36  * In order to make conj(cacosh(z))=cacosh(conj(z)),
  37  * we define
  38  *      cacosh z = sign(Im(z))*i cacos z .
  39  *
  40  */
  41 /* INDENT ON */
  42
  43 #include "libm.h"       /* fabs/isnan/isinf/signbit */
  44 #include "complex_wrapper.h"
  45
  46 /* need to work on special cases according to spec */
  47
  48 dcomplex
  49 cacosh(dcomplex z) {
  50         dcomplex w, ans;
  51         double x, y;
  52
  53         w = cacos(z);
  54         x = D_RE(z);
  55         y = D_IM(z);
  56         if (isnan(y)) {
  57                 D_IM(ans) = y + y;
  58                 if (isinf(x))
  59                         D_RE(ans) = fabs(x);
  60                 else
  61                         D_RE(ans) = y;
  62         } else if (signbit(y) == 0) {
  63                 D_RE(ans) = -D_IM(w);
  64                 D_IM(ans) = D_RE(w);
  65         } else {
  66                 D_RE(ans) = D_IM(w);
  67                 D_IM(ans) = -D_RE(w);
  68         }
  69         return (ans);
  70 }