kc3-lang/libquadmath/math/ctanq.c

Branch - branch -master

• Show log

  Commit

• Hash : 4f659ab9
  Author : Thomas de Grivel
  Date : 2025-11-02T19:33:45
  

  initial commit
  

Download

• math/ctanq.c

• /* Complex tangent function for a complex float type.
     Copyright (C) 1997-2018 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
     Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, see
     <http://www.gnu.org/licenses/>.  */
  
  #include "quadmath-imp.h"
  
  __complex128
  ctanq (__complex128 x)
  {
    __complex128 res;
  
    if (__glibc_unlikely (!finiteq (__real__ x) || !finiteq (__imag__ x)))
      {
        if (isinfq (__imag__ x))
  	{
  	  if (finiteq (__real__ x) && fabsq (__real__ x) > 1)
  	    {
  	      __float128 sinrx, cosrx;
  	      sincosq (__real__ x, &sinrx, &cosrx);
  	      __real__ res = copysignq (0, sinrx * cosrx);
  	    }
  	  else
  	    __real__ res = copysignq (0, __real__ x);
  	  __imag__ res = copysignq (1, __imag__ x);
  	}
        else if (__real__ x == 0)
  	{
  	  res = x;
  	}
        else
  	{
  	  __real__ res = nanq ("");
  	  if (__imag__ x == 0)
  	    __imag__ res = __imag__ x;
  	  else
  	    __imag__ res = nanq ("");
  
  	  if (isinfq (__real__ x))
  	    feraiseexcept (FE_INVALID);
  	}
      }
    else
      {
        __float128 sinrx, cosrx;
        __float128 den;
        const int t = (int) ((FLT128_MAX_EXP - 1) * M_LN2q / 2);
  
        /* tan(x+iy) = (sin(2x) + i*sinh(2y))/(cos(2x) + cosh(2y))
  	 = (sin(x)*cos(x) + i*sinh(y)*cosh(y)/(cos(x)^2 + sinh(y)^2). */
  
        if (__glibc_likely (fabsq (__real__ x) > FLT128_MIN))
  	{
  	  sincosq (__real__ x, &sinrx, &cosrx);
  	}
        else
  	{
  	  sinrx = __real__ x;
  	  cosrx = 1;
  	}
  
        if (fabsq (__imag__ x) > t)
  	{
  	  /* Avoid intermediate overflow when the real part of the
  	     result may be subnormal.  Ignoring negligible terms, the
  	     imaginary part is +/- 1, the real part is
  	     sin(x)*cos(x)/sinh(y)^2 = 4*sin(x)*cos(x)/exp(2y).  */
  	  __float128 exp_2t = expq (2 * t);
  
  	  __imag__ res = copysignq (1, __imag__ x);
  	  __real__ res = 4 * sinrx * cosrx;
  	  __imag__ x = fabsq (__imag__ x);
  	  __imag__ x -= t;
  	  __real__ res /= exp_2t;
  	  if (__imag__ x > t)
  	    {
  	      /* Underflow (original imaginary part of x has absolute
  		 value > 2t).  */
  	      __real__ res /= exp_2t;
  	    }
  	  else
  	    __real__ res /= expq (2 * __imag__ x);
  	}
        else
  	{
  	  __float128 sinhix, coshix;
  	  if (fabsq (__imag__ x) > FLT128_MIN)
  	    {
  	      sinhix = sinhq (__imag__ x);
  	      coshix = coshq (__imag__ x);
  	    }
  	  else
  	    {
  	      sinhix = __imag__ x;
  	      coshix = 1;
  	    }
  
  	  if (fabsq (sinhix) > fabsq (cosrx) * FLT128_EPSILON)
  	    den = cosrx * cosrx + sinhix * sinhix;
  	  else
  	    den = cosrx * cosrx;
  	  __real__ res = sinrx * cosrx / den;
  	  __imag__ res = sinhix * coshix / den;
  	}
        math_check_force_underflow_complex (res);
      }
  
    return res;
  }
  

Download