mirror of
https://https.git.savannah.gnu.org/git/gnulib.git
synced 2026-04-28 06:33:36 +00:00
137 lines
4.0 KiB
C
137 lines
4.0 KiB
C
/* sin (sine) function with 'long double' argument.
|
|
|
|
Copyright (C) 2003-2026 Free Software Foundation, Inc.
|
|
|
|
This file 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 3 of the
|
|
License, or (at your option) any later version.
|
|
|
|
This file 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 this program. If not, see <https://www.gnu.org/licenses/>. */
|
|
|
|
/* s_sinl.c -- long double version of s_sin.c.
|
|
* Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz.
|
|
*/
|
|
|
|
/*
|
|
* ====================================================
|
|
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
|
|
*
|
|
* Developed at SunPro, a Sun Microsystems, Inc. business.
|
|
* Permission to use, copy, modify, and distribute this
|
|
* software is freely granted, provided that this notice
|
|
* is preserved.
|
|
* ====================================================
|
|
*/
|
|
|
|
#include <config.h>
|
|
|
|
/* Specification. */
|
|
#include <math.h>
|
|
|
|
#if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
|
|
|
|
long double
|
|
sinl (long double x)
|
|
{
|
|
return sin (x);
|
|
}
|
|
|
|
#else
|
|
|
|
/* Code based on glibc/sysdeps/ieee754/ldbl-128/s_sinl.c. */
|
|
|
|
/* sinl(x)
|
|
* Return sine function of x.
|
|
*
|
|
* kernel function:
|
|
* __kernel_sinl ... sine function on [-pi/4,pi/4]
|
|
* __kernel_cosl ... cosine function on [-pi/4,pi/4]
|
|
* __ieee754_rem_pio2l ... argument reduction routine
|
|
*
|
|
* Method.
|
|
* Let S,C and T denote the sin, cos and tan respectively on
|
|
* [-PI/4, +PI/4]. Reduce the argument x to y1+y2 = x-k*pi/2
|
|
* in [-pi/4 , +pi/4], and let n = k mod 4.
|
|
* We have
|
|
*
|
|
* n sin(x) cos(x) tan(x)
|
|
* ----------------------------------------------------------
|
|
* 0 S C T
|
|
* 1 C -S -1/T
|
|
* 2 -S -C T
|
|
* 3 -C S -1/T
|
|
* ----------------------------------------------------------
|
|
*
|
|
* Special cases:
|
|
* Let trig be any of sin, cos, or tan.
|
|
* trig(+-INF) is NaN, with signals;
|
|
* trig(NaN) is that NaN;
|
|
*
|
|
* Accuracy:
|
|
* TRIG(x) returns trig(x) nearly rounded
|
|
*/
|
|
|
|
# include "trigl.h"
|
|
|
|
long double
|
|
sinl (long double x)
|
|
{
|
|
/* sinl(NaN) is NaN */
|
|
if (isnanl (x))
|
|
return x;
|
|
|
|
/* |x| ~< pi/4 */
|
|
if (x >= -0.7853981633974483096156608458198757210492
|
|
&& x <= 0.7853981633974483096156608458198757210492)
|
|
{
|
|
long double z = 0.0L;
|
|
return kernel_sinl (x, z, 0);
|
|
}
|
|
|
|
/* sinl(Inf) is NaN, sinl(0) is 0 */
|
|
else if (x + x == x)
|
|
return x - x; /* NaN */
|
|
|
|
/* argument reduction needed */
|
|
else
|
|
{
|
|
long double y[2];
|
|
int n = ieee754_rem_pio2l (x, y);
|
|
switch (n & 3)
|
|
{
|
|
case 0:
|
|
return kernel_sinl (y[0], y[1], 1);
|
|
case 1:
|
|
return kernel_cosl (y[0], y[1]);
|
|
case 2:
|
|
return -kernel_sinl (y[0], y[1], 1);
|
|
default:
|
|
return -kernel_cosl (y[0], y[1]);
|
|
}
|
|
}
|
|
}
|
|
|
|
#endif
|
|
|
|
#if 0
|
|
int
|
|
main (void)
|
|
{
|
|
printf ("%.16Lg\n", sinl (0.7853981633974483096156608458198757210492));
|
|
printf ("%.16Lg\n", sinl (0.7853981633974483096156608458198757210492 *29));
|
|
printf ("%.16Lg\n", sinl (0.7853981633974483096156608458198757210492 *2));
|
|
printf ("%.16Lg\n", sinl (0.7853981633974483096156608458198757210492 *30));
|
|
printf ("%.16Lg\n", sinl (0.7853981633974483096156608458198757210492 *4));
|
|
printf ("%.16Lg\n", sinl (0.7853981633974483096156608458198757210492 *32));
|
|
printf ("%.16Lg\n", sinl (0.7853981633974483096156608458198757210492 *2/3));
|
|
printf ("%.16Lg\n", sinl (0.7853981633974483096156608458198757210492 *4/3));
|
|
}
|
|
#endif
|