math/s_cexp.c

   1 /* Return value of complex exponential function for double complex value.
   2    Copyright (C) 1997-2012 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 __cexp (__complex__ double x)
  28 {
  29   __complex__ double retval;
  30   int rcls = fpclassify (__real__ x);
  31   int icls = fpclassify (__imag__ x);
  32
  33   if (__builtin_expect (rcls >= FP_ZERO, 1))
  34     {
  35       /* Real part is finite.  */
  36       if (__builtin_expect (icls >= FP_ZERO, 1))
  37         {
  38           /* Imaginary part is finite.  */
  39           const int t = (int) ((DBL_MAX_EXP - 1) * M_LN2);
  40           double sinix, cosix;
  41
  42           __sincos (__imag__ x, &sinix, &cosix);
  43
  44           if (__real__ x > t)
  45             {
  46               double exp_t = __ieee754_exp (t);
  47               __real__ x -= t;
  48               sinix *= exp_t;
  49               cosix *= exp_t;
  50               if (__real__ x > t)
  51                 {
  52                   __real__ x -= t;
  53                   sinix *= exp_t;
  54                   cosix *= exp_t;
  55                 }
  56             }
  57           if (__real__ x > t)
  58             {
  59               /* Overflow (original real part of x > 3t).  */
  60               __real__ retval = DBL_MAX * cosix;
  61               __imag__ retval = DBL_MAX * sinix;
  62             }
  63           else
  64             {
  65               double exp_val = __ieee754_exp (__real__ x);
  66               __real__ retval = exp_val * cosix;
  67               __imag__ retval = exp_val * sinix;
  68             }
  69         }
  70       else
  71         {
  72           /* If the imaginary part is +-inf or NaN and the real part
  73              is not +-inf the result is NaN + iNaN.  */
  74           __real__ retval = __nan ("");
  75           __imag__ retval = __nan ("");
  76
  77           feraiseexcept (FE_INVALID);
  78         }
  79     }
  80   else if (__builtin_expect (rcls == FP_INFINITE, 1))
  81     {
  82       /* Real part is infinite.  */
  83       if (__builtin_expect (icls >= FP_ZERO, 1))
  84         {
  85           /* Imaginary part is finite.  */
  86           double value = signbit (__real__ x) ? 0.0 : HUGE_VAL;
  87
  88           if (icls == FP_ZERO)
  89             {
  90               /* Imaginary part is 0.0.  */
  91               __real__ retval = value;
  92               __imag__ retval = __imag__ x;
  93             }
  94           else
  95             {
  96               double sinix, cosix;
  97
  98               __sincos (__imag__ x, &sinix, &cosix);
  99
 100               __real__ retval = __copysign (value, cosix);
 101               __imag__ retval = __copysign (value, sinix);
 102             }
 103         }
 104       else if (signbit (__real__ x) == 0)
 105         {
 106           __real__ retval = HUGE_VAL;
 107           __imag__ retval = __nan ("");
 108
 109           if (icls == FP_INFINITE)
 110             feraiseexcept (FE_INVALID);
 111         }
 112       else
 113         {
 114           __real__ retval = 0.0;
 115           __imag__ retval = __copysign (0.0, __imag__ x);
 116         }
 117     }
 118   else
 119     {
 120       /* If the real part is NaN the result is NaN + iNaN.  */
 121       __real__ retval = __nan ("");
 122       __imag__ retval = __nan ("");
 123
 124       if (rcls != FP_NAN || icls != FP_NAN)
 125         feraiseexcept (FE_INVALID);
 126     }
 127
 128   return retval;
 129 }
 130 weak_alias (__cexp, cexp)
 131 #ifdef NO_LONG_DOUBLE
 132 strong_alias (__cexp, __cexpl)
 133 weak_alias (__cexp, cexpl)
 134 #endif