kc3-lang/libquadmath/math/clogq.c

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

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• math/clogq.c

• /* Compute complex natural logarithm.
     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
  clogq (__complex128 x)
  {
    __complex128 result;
    int rcls = fpclassifyq (__real__ x);
    int icls = fpclassifyq (__imag__ x);
  
    if (__glibc_unlikely (rcls == QUADFP_ZERO && icls == QUADFP_ZERO))
      {
        /* Real and imaginary part are 0.0.  */
        __imag__ result = signbitq (__real__ x) ? (__float128) M_PIq : 0;
        __imag__ result = copysignq (__imag__ result, __imag__ x);
        /* Yes, the following line raises an exception.  */
        __real__ result = -1 / fabsq (__real__ x);
      }
    else if (__glibc_likely (rcls != QUADFP_NAN && icls != QUADFP_NAN))
      {
        /* Neither real nor imaginary part is NaN.  */
        __float128 absx = fabsq (__real__ x), absy = fabsq (__imag__ x);
        int scale = 0;
  
        if (absx < absy)
  	{
  	  __float128 t = absx;
  	  absx = absy;
  	  absy = t;
  	}
  
        if (absx > FLT128_MAX / 2)
  	{
  	  scale = -1;
  	  absx = scalbnq (absx, scale);
  	  absy = (absy >= FLT128_MIN * 2 ? scalbnq (absy, scale) : 0);
  	}
        else if (absx < FLT128_MIN && absy < FLT128_MIN)
  	{
  	  scale = FLT128_MANT_DIG;
  	  absx = scalbnq (absx, scale);
  	  absy = scalbnq (absy, scale);
  	}
  
        if (absx == 1 && scale == 0)
  	{
  	  __real__ result = log1pq (absy * absy) / 2;
  	  math_check_force_underflow_nonneg (__real__ result);
  	}
        else if (absx > 1 && absx < 2 && absy < 1 && scale == 0)
  	{
  	  __float128 d2m1 = (absx - 1) * (absx + 1);
  	  if (absy >= FLT128_EPSILON)
  	    d2m1 += absy * absy;
  	  __real__ result = log1pq (d2m1) / 2;
  	}
        else if (absx < 1
  	       && absx >= 0.5Q
  	       && absy < FLT128_EPSILON / 2
  	       && scale == 0)
  	{
  	  __float128 d2m1 = (absx - 1) * (absx + 1);
  	  __real__ result = log1pq (d2m1) / 2;
  	}
        else if (absx < 1
  	       && absx >= 0.5Q
  	       && scale == 0
  	       && absx * absx + absy * absy >= 0.5Q)
  	{
  	  __float128 d2m1 = __quadmath_x2y2m1q (absx, absy);
  	  __real__ result = log1pq (d2m1) / 2;
  	}
        else
  	{
  	  __float128 d = hypotq (absx, absy);
  	  __real__ result = logq (d) - scale * (__float128) M_LN2q;
  	}
  
        __imag__ result = atan2q (__imag__ x, __real__ x);
      }
    else
      {
        __imag__ result = nanq ("");
        if (rcls == QUADFP_INFINITE || icls == QUADFP_INFINITE)
  	/* Real or imaginary part is infinite.  */
  	__real__ result = HUGE_VALQ;
        else
  	__real__ result = nanq ("");
      }
  
    return result;
  }
  

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