math/s_csin.c

   1 /* Complex sine function for double.
   2    Copyright (C) 1997-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <complex.h>
  21 #include <fenv.h>
  22 #include <math.h>
  23 #include <math_private.h>
  24 #include <float.h>
  25
  26 __complex__ double
  27 __csin (__complex__ double x)
  28 {
  29   __complex__ double retval;
  30   int negate = signbit (__real__ x);
  31   int rcls = fpclassify (__real__ x);
  32   int icls = fpclassify (__imag__ x);
  33
  34   __real__ x = fabs (__real__ x);
  35
  36   if (__glibc_likely (icls >= FP_ZERO))
  37     {
  38       /* Imaginary part is finite.  */
  39       if (__glibc_likely (rcls >= FP_ZERO))
  40         {
  41           /* Real part is finite.  */
  42           const int t = (int) ((DBL_MAX_EXP - 1) * M_LN2);
  43           double sinix, cosix;
  44
  45           if (__glibc_likely (rcls != FP_SUBNORMAL))
  46             {
  47               __sincos (__real__ x, &sinix, &cosix);
  48             }
  49           else
  50             {
  51               sinix = __real__ x;
  52               cosix = 1.0;
  53             }
  54
  55           if (fabs (__imag__ x) > t)
  56             {
  57               double exp_t = __ieee754_exp (t);
  58               double ix = fabs (__imag__ x);
  59               if (signbit (__imag__ x))
  60                 cosix = -cosix;
  61               ix -= t;
  62               sinix *= exp_t / 2.0;
  63               cosix *= exp_t / 2.0;
  64               if (ix > t)
  65                 {
  66                   ix -= t;
  67                   sinix *= exp_t;
  68                   cosix *= exp_t;
  69                 }
  70               if (ix > t)
  71                 {
  72                   /* Overflow (original imaginary part of x > 3t).  */
  73                   __real__ retval = DBL_MAX * sinix;
  74                   __imag__ retval = DBL_MAX * cosix;
  75                 }
  76               else
  77                 {
  78                   double exp_val = __ieee754_exp (ix);
  79                   __real__ retval = exp_val * sinix;
  80                   __imag__ retval = exp_val * cosix;
  81                 }
  82             }
  83           else
  84             {
  85               __real__ retval = __ieee754_cosh (__imag__ x) * sinix;
  86               __imag__ retval = __ieee754_sinh (__imag__ x) * cosix;
  87             }
  88
  89           if (negate)
  90             __real__ retval = -__real__ retval;
  91
  92           if (fabs (__real__ retval) < DBL_MIN)
  93             {
  94               volatile double force_underflow
  95                 = __real__ retval * __real__ retval;
  96               (void) force_underflow;
  97             }
  98           if (fabs (__imag__ retval) < DBL_MIN)
  99             {
 100               volatile double force_underflow
 101                 = __imag__ retval * __imag__ retval;
 102               (void) force_underflow;
 103             }
 104         }
 105       else
 106         {
 107           if (icls == FP_ZERO)
 108             {
 109               /* Imaginary part is 0.0.  */
 110               __real__ retval = __nan ("");
 111               __imag__ retval = __imag__ x;
 112
 113               if (rcls == FP_INFINITE)
 114                 feraiseexcept (FE_INVALID);
 115             }
 116           else
 117             {
 118               __real__ retval = __nan ("");
 119               __imag__ retval = __nan ("");
 120
 121               feraiseexcept (FE_INVALID);
 122             }
 123         }
 124     }
 125   else if (icls == FP_INFINITE)
 126     {
 127       /* Imaginary part is infinite.  */
 128       if (rcls == FP_ZERO)
 129         {
 130           /* Real part is 0.0.  */
 131           __real__ retval = __copysign (0.0, negate ? -1.0 : 1.0);
 132           __imag__ retval = __imag__ x;
 133         }
 134       else if (rcls > FP_ZERO)
 135         {
 136           /* Real part is finite.  */
 137           double sinix, cosix;
 138
 139           if (__glibc_likely (rcls != FP_SUBNORMAL))
 140             {
 141               __sincos (__real__ x, &sinix, &cosix);
 142             }
 143           else
 144             {
 145               sinix = __real__ x;
 146               cosix = 1.0;
 147             }
 148
 149           __real__ retval = __copysign (HUGE_VAL, sinix);
 150           __imag__ retval = __copysign (HUGE_VAL, cosix);
 151
 152           if (negate)
 153             __real__ retval = -__real__ retval;
 154           if (signbit (__imag__ x))
 155             __imag__ retval = -__imag__ retval;
 156         }
 157       else
 158         {
 159           /* The addition raises the invalid exception.  */
 160           __real__ retval = __nan ("");
 161           __imag__ retval = HUGE_VAL;
 162
 163           if (rcls == FP_INFINITE)
 164             feraiseexcept (FE_INVALID);
 165         }
 166     }
 167   else
 168     {
 169       if (rcls == FP_ZERO)
 170         __real__ retval = __copysign (0.0, negate ? -1.0 : 1.0);
 171       else
 172         __real__ retval = __nan ("");
 173       __imag__ retval = __nan ("");
 174     }
 175
 176   return retval;
 177 }
 178 weak_alias (__csin, csin)
 179 #ifdef NO_LONG_DOUBLE
 180 strong_alias (__csin, __csinl)
 181 weak_alias (__csin, csinl)
 182 #endif