Blame sysdeps/ieee754/ldbl-96/k_sinl.c

Packit 6c4009
/* Quad-precision floating point sine on <-pi/4,pi/4>.
Packit 6c4009
   Copyright (C) 1999-2018 Free Software Foundation, Inc.
Packit 6c4009
   This file is part of the GNU C Library.
Packit 6c4009
   Based on quad-precision sine by Jakub Jelinek <jj@ultra.linux.cz>
Packit 6c4009
Packit 6c4009
   The GNU C Library is free software; you can redistribute it and/or
Packit 6c4009
   modify it under the terms of the GNU Lesser General Public
Packit 6c4009
   License as published by the Free Software Foundation; either
Packit 6c4009
   version 2.1 of the License, or (at your option) any later version.
Packit 6c4009
Packit 6c4009
   The GNU C Library is distributed in the hope that it will be useful,
Packit 6c4009
   but WITHOUT ANY WARRANTY; without even the implied warranty of
Packit 6c4009
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Packit 6c4009
   Lesser General Public License for more details.
Packit 6c4009
Packit 6c4009
   You should have received a copy of the GNU Lesser General Public
Packit 6c4009
   License along with the GNU C Library; if not, see
Packit 6c4009
   <http://www.gnu.org/licenses/>.  */
Packit 6c4009
Packit 6c4009
/* The polynomials have not been optimized for extended-precision and
Packit 6c4009
   may contain more terms than needed.  */
Packit 6c4009
Packit 6c4009
#include <float.h>
Packit 6c4009
#include <math.h>
Packit 6c4009
#include <math_private.h>
Packit 6c4009
#include <math-underflow.h>
Packit 6c4009
Packit 6c4009
/* The polynomials have not been optimized for extended-precision and
Packit 6c4009
   may contain more terms than needed.  */
Packit 6c4009
Packit 6c4009
static const long double c[] = {
Packit 6c4009
#define ONE c[0]
Packit 6c4009
 1.00000000000000000000000000000000000E+00L,
Packit 6c4009
Packit 6c4009
/* cos x ~ ONE + x^2 ( SCOS1 + SCOS2 * x^2 + ... + SCOS4 * x^6 + SCOS5 * x^8 )
Packit 6c4009
   x in <0,1/256>  */
Packit 6c4009
#define SCOS1 c[1]
Packit 6c4009
#define SCOS2 c[2]
Packit 6c4009
#define SCOS3 c[3]
Packit 6c4009
#define SCOS4 c[4]
Packit 6c4009
#define SCOS5 c[5]
Packit 6c4009
-5.00000000000000000000000000000000000E-01L,
Packit 6c4009
 4.16666666666666666666666666556146073E-02L,
Packit 6c4009
-1.38888888888888888888309442601939728E-03L,
Packit 6c4009
 2.48015873015862382987049502531095061E-05L,
Packit 6c4009
-2.75573112601362126593516899592158083E-07L,
Packit 6c4009
Packit 6c4009
/* sin x ~ ONE * x + x^3 ( SIN1 + SIN2 * x^2 + ... + SIN7 * x^12 + SIN8 * x^14 )
Packit 6c4009
   x in <0,0.1484375>  */
Packit 6c4009
#define SIN1 c[6]
Packit 6c4009
#define SIN2 c[7]
Packit 6c4009
#define SIN3 c[8]
Packit 6c4009
#define SIN4 c[9]
Packit 6c4009
#define SIN5 c[10]
Packit 6c4009
#define SIN6 c[11]
Packit 6c4009
#define SIN7 c[12]
Packit 6c4009
#define SIN8 c[13]
Packit 6c4009
-1.66666666666666666666666666666666538e-01L,
Packit 6c4009
 8.33333333333333333333333333307532934e-03L,
Packit 6c4009
-1.98412698412698412698412534478712057e-04L,
Packit 6c4009
 2.75573192239858906520896496653095890e-06L,
Packit 6c4009
-2.50521083854417116999224301266655662e-08L,
Packit 6c4009
 1.60590438367608957516841576404938118e-10L,
Packit 6c4009
-7.64716343504264506714019494041582610e-13L,
Packit 6c4009
 2.81068754939739570236322404393398135e-15L,
Packit 6c4009
Packit 6c4009
/* sin x ~ ONE * x + x^3 ( SSIN1 + SSIN2 * x^2 + ... + SSIN4 * x^6 + SSIN5 * x^8 )
Packit 6c4009
   x in <0,1/256>  */
Packit 6c4009
#define SSIN1 c[14]
Packit 6c4009
#define SSIN2 c[15]
Packit 6c4009
#define SSIN3 c[16]
Packit 6c4009
#define SSIN4 c[17]
Packit 6c4009
#define SSIN5 c[18]
Packit 6c4009
-1.66666666666666666666666666666666659E-01L,
Packit 6c4009
 8.33333333333333333333333333146298442E-03L,
Packit 6c4009
-1.98412698412698412697726277416810661E-04L,
Packit 6c4009
 2.75573192239848624174178393552189149E-06L,
Packit 6c4009
-2.50521016467996193495359189395805639E-08L,
Packit 6c4009
};
Packit 6c4009
Packit 6c4009
#define SINCOSL_COS_HI 0
Packit 6c4009
#define SINCOSL_COS_LO 1
Packit 6c4009
#define SINCOSL_SIN_HI 2
Packit 6c4009
#define SINCOSL_SIN_LO 3
Packit 6c4009
extern const long double __sincosl_table[];
Packit 6c4009
Packit 6c4009
long double
Packit 6c4009
__kernel_sinl(long double x, long double y, int iy)
Packit 6c4009
{
Packit 6c4009
  long double absx, h, l, z, sin_l, cos_l_m1;
Packit 6c4009
  int index;
Packit 6c4009
Packit 6c4009
  absx = fabsl (x);
Packit 6c4009
  if (absx < 0.1484375L)
Packit 6c4009
    {
Packit 6c4009
      /* Argument is small enough to approximate it by a Chebyshev
Packit 6c4009
	 polynomial of degree 17.  */
Packit 6c4009
      if (absx < 0x1p-33L)
Packit 6c4009
	{
Packit 6c4009
	  math_check_force_underflow (x);
Packit 6c4009
	  if (!((int)x)) return x;	/* generate inexact */
Packit 6c4009
	}
Packit 6c4009
      z = x * x;
Packit 6c4009
      return x + (x * (z*(SIN1+z*(SIN2+z*(SIN3+z*(SIN4+
Packit 6c4009
		       z*(SIN5+z*(SIN6+z*(SIN7+z*SIN8)))))))));
Packit 6c4009
    }
Packit 6c4009
  else
Packit 6c4009
    {
Packit 6c4009
      /* So that we don't have to use too large polynomial,  we find
Packit 6c4009
	 l and h such that x = l + h,  where fabsl(l) <= 1.0/256 with 83
Packit 6c4009
	 possible values for h.  We look up cosl(h) and sinl(h) in
Packit 6c4009
	 pre-computed tables,  compute cosl(l) and sinl(l) using a
Packit 6c4009
	 Chebyshev polynomial of degree 10(11) and compute
Packit 6c4009
	 sinl(h+l) = sinl(h)cosl(l) + cosl(h)sinl(l).  */
Packit 6c4009
      index = (int) (128 * (absx - (0.1484375L - 1.0L / 256.0L)));
Packit 6c4009
      h = 0.1484375L + index / 128.0;
Packit 6c4009
      index *= 4;
Packit 6c4009
      if (iy)
Packit 6c4009
	l = (x < 0 ? -y : y) - (h - absx);
Packit 6c4009
      else
Packit 6c4009
	l = absx - h;
Packit 6c4009
      z = l * l;
Packit 6c4009
      sin_l = l*(ONE+z*(SSIN1+z*(SSIN2+z*(SSIN3+z*(SSIN4+z*SSIN5)))));
Packit 6c4009
      cos_l_m1 = z*(SCOS1+z*(SCOS2+z*(SCOS3+z*(SCOS4+z*SCOS5))));
Packit 6c4009
      z = __sincosl_table [index + SINCOSL_SIN_HI]
Packit 6c4009
	  + (__sincosl_table [index + SINCOSL_SIN_LO]
Packit 6c4009
	     + (__sincosl_table [index + SINCOSL_SIN_HI] * cos_l_m1)
Packit 6c4009
	     + (__sincosl_table [index + SINCOSL_COS_HI] * sin_l));
Packit 6c4009
      return (x < 0) ? -z : z;
Packit 6c4009
    }
Packit 6c4009
}