math/s_csin_template.c

   1 /* Complex sine function for float types.
   2    Copyright (C) 1997-2020 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    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <complex.h>
  21 #include <fenv.h>
  22 #include <math.h>
  23 #include <math_private.h>
  24 #include <math-underflow.h>
  25 #include <float.h>
  26
  27 CFLOAT
  28 M_DECL_FUNC (__csin) (CFLOAT x)
  29 {
  30   CFLOAT retval;
  31   int negate = signbit (__real__ x);
  32   int rcls = fpclassify (__real__ x);
  33   int icls = fpclassify (__imag__ x);
  34
  35   __real__ x = M_FABS (__real__ x);
  36
  37   if (__glibc_likely (icls >= FP_ZERO))
  38     {
  39       /* Imaginary part is finite.  */
  40       if (__glibc_likely (rcls >= FP_ZERO))
  41         {
  42           /* Real part is finite.  */
  43           const int t = (int) ((M_MAX_EXP - 1) * M_MLIT (M_LN2));
  44           FLOAT sinix, cosix;
  45
  46           if (__glibc_likely (__real__ x > M_MIN))
  47             {
  48               M_SINCOS (__real__ x, &sinix, &cosix);
  49             }
  50           else
  51             {
  52               sinix = __real__ x;
  53               cosix = 1;
  54             }
  55
  56           if (negate)
  57             sinix = -sinix;
  58
  59           if (M_FABS (__imag__ x) > t)
  60             {
  61               FLOAT exp_t = M_EXP (t);
  62               FLOAT ix = M_FABS (__imag__ x);
  63               if (signbit (__imag__ x))
  64                 cosix = -cosix;
  65               ix -= t;
  66               sinix *= exp_t / 2;
  67               cosix *= exp_t / 2;
  68               if (ix > t)
  69                 {
  70                   ix -= t;
  71                   sinix *= exp_t;
  72                   cosix *= exp_t;
  73                 }
  74               if (ix > t)
  75                 {
  76                   /* Overflow (original imaginary part of x > 3t).  */
  77                   __real__ retval = M_MAX * sinix;
  78                   __imag__ retval = M_MAX * cosix;
  79                 }
  80               else
  81                 {
  82                   FLOAT exp_val = M_EXP (ix);
  83                   __real__ retval = exp_val * sinix;
  84                   __imag__ retval = exp_val * cosix;
  85                 }
  86             }
  87           else
  88             {
  89               __real__ retval = M_COSH (__imag__ x) * sinix;
  90               __imag__ retval = M_SINH (__imag__ x) * cosix;
  91             }
  92
  93           math_check_force_underflow_complex (retval);
  94         }
  95       else
  96         {
  97           if (icls == FP_ZERO)
  98             {
  99               /* Imaginary part is 0.0.  */
 100               __real__ retval = __real__ x - __real__ x;
 101               __imag__ retval = __imag__ x;
 102             }
 103           else
 104             {
 105               __real__ retval = M_NAN;
 106               __imag__ retval = M_NAN;
 107
 108               feraiseexcept (FE_INVALID);
 109             }
 110         }
 111     }
 112   else if (icls == FP_INFINITE)
 113     {
 114       /* Imaginary part is infinite.  */
 115       if (rcls == FP_ZERO)
 116         {
 117           /* Real part is 0.0.  */
 118           __real__ retval = M_COPYSIGN (0, negate ? -1 : 1);
 119           __imag__ retval = __imag__ x;
 120         }
 121       else if (rcls > FP_ZERO)
 122         {
 123           /* Real part is finite.  */
 124           FLOAT sinix, cosix;
 125
 126           if (__glibc_likely (__real__ x > M_MIN))
 127             {
 128               M_SINCOS (__real__ x, &sinix, &cosix);
 129             }
 130           else
 131             {
 132               sinix = __real__ x;
 133               cosix = 1;
 134             }
 135
 136           __real__ retval = M_COPYSIGN (M_HUGE_VAL, sinix);
 137           __imag__ retval = M_COPYSIGN (M_HUGE_VAL, cosix);
 138
 139           if (negate)
 140             __real__ retval = -__real__ retval;
 141           if (signbit (__imag__ x))
 142             __imag__ retval = -__imag__ retval;
 143         }
 144       else
 145         {
 146           __real__ retval = __real__ x - __real__ x;
 147           __imag__ retval = M_HUGE_VAL;
 148         }
 149     }
 150   else
 151     {
 152       if (rcls == FP_ZERO)
 153         __real__ retval = M_COPYSIGN (0, negate ? -1 : 1);
 154       else
 155         __real__ retval = M_NAN;
 156       __imag__ retval = M_NAN;
 157     }
 158
 159   return retval;
 160 }
 161
 162 declare_mgen_alias (__csin, csin)