mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-30 08:40:07 +00:00
103 lines
3.1 KiB
C
103 lines
3.1 KiB
C
/* e_asinf.c -- float version of e_asin.c.
|
|
* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
|
|
*/
|
|
|
|
/*
|
|
* ====================================================
|
|
* 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.
|
|
* ====================================================
|
|
*/
|
|
|
|
/*
|
|
Modifications for single precision expansion are
|
|
Copyright (C) 2001 Stephen L. Moshier <moshier@na-net.ornl.gov>
|
|
and are incorporated herein by permission of the author. The author
|
|
reserves the right to distribute this material elsewhere under different
|
|
copying permissions. These modifications are distributed here under
|
|
the following terms:
|
|
|
|
This 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.
|
|
|
|
This 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 this library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#if defined(LIBM_SCCS) && !defined(lint)
|
|
static char rcsid[] = "$NetBSD: e_asinf.c,v 1.5 1995/05/12 04:57:25 jtc Exp $";
|
|
#endif
|
|
|
|
#include <math.h>
|
|
#include <math_private.h>
|
|
|
|
static const float
|
|
one = 1.0000000000e+00, /* 0x3F800000 */
|
|
huge = 1.000e+30,
|
|
|
|
pio2_hi = 1.57079637050628662109375f,
|
|
pio2_lo = -4.37113900018624283e-8f,
|
|
pio4_hi = 0.785398185253143310546875f,
|
|
|
|
/* asin x = x + x^3 p(x^2)
|
|
-0.5 <= x <= 0.5;
|
|
Peak relative error 4.8e-9 */
|
|
p0 = 1.666675248e-1f,
|
|
p1 = 7.495297643e-2f,
|
|
p2 = 4.547037598e-2f,
|
|
p3 = 2.417951451e-2f,
|
|
p4 = 4.216630880e-2f;
|
|
|
|
float __ieee754_asinf(float x)
|
|
{
|
|
float t,w,p,q,c,r,s;
|
|
int32_t hx,ix;
|
|
GET_FLOAT_WORD(hx,x);
|
|
ix = hx&0x7fffffff;
|
|
if(ix==0x3f800000) {
|
|
/* asin(1)=+-pi/2 with inexact */
|
|
return x*pio2_hi+x*pio2_lo;
|
|
} else if(ix> 0x3f800000) { /* |x|>= 1 */
|
|
return (x-x)/(x-x); /* asin(|x|>1) is NaN */
|
|
} else if (ix<0x3f000000) { /* |x|<0.5 */
|
|
if(ix<0x32000000) { /* if |x| < 2**-27 */
|
|
if(huge+x>one) return x;/* return x with inexact if x!=0*/
|
|
} else {
|
|
t = x*x;
|
|
w = t * (p0 + t * (p1 + t * (p2 + t * (p3 + t * p4))));
|
|
return x+x*w;
|
|
}
|
|
}
|
|
/* 1> |x|>= 0.5 */
|
|
w = one-fabsf(x);
|
|
t = w*0.5f;
|
|
p = t * (p0 + t * (p1 + t * (p2 + t * (p3 + t * p4))));
|
|
s = __ieee754_sqrtf(t);
|
|
if(ix>=0x3F79999A) { /* if |x| > 0.975 */
|
|
t = pio2_hi-(2.0f*(s+s*p)-pio2_lo);
|
|
} else {
|
|
int32_t iw;
|
|
w = s;
|
|
GET_FLOAT_WORD(iw,w);
|
|
SET_FLOAT_WORD(w,iw&0xfffff000);
|
|
c = (t-w*w)/(s+w);
|
|
r = p;
|
|
p = 2.0f*s*r-(pio2_lo-2.0f*c);
|
|
q = pio4_hi-2.0f*w;
|
|
t = pio4_hi-(p-q);
|
|
}
|
|
if(hx>0) return t; else return -t;
|
|
}
|
|
strong_alias (__ieee754_asinf, __asinf_finite)
|