106 lines
3.2 KiB
C
106 lines
3.2 KiB
C
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/* e_asinf.c -- float version of e_asin.c.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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Modifications for single precision expansion are
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Copyright (C) 2001 Stephen L. Moshier <moshier@na-net.ornl.gov>
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and are incorporated herein by permission of the author. The author
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reserves the right to distribute this material elsewhere under different
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copying permissions. These modifications are distributed here under
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the following terms:
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, see
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<https://www.gnu.org/licenses/>. */
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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: e_asinf.c,v 1.5 1995/05/12 04:57:25 jtc Exp $";
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#endif
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#include <float.h>
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#include <math.h>
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#include <math_private.h>
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#include <math-underflow.h>
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#include <libm-alias-finite.h>
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static const float
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one = 1.0000000000e+00, /* 0x3F800000 */
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huge = 1.000e+30,
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pio2_hi = 1.57079637050628662109375f,
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pio2_lo = -4.37113900018624283e-8f,
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pio4_hi = 0.785398185253143310546875f,
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/* asin x = x + x^3 p(x^2)
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-0.5 <= x <= 0.5;
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Peak relative error 4.8e-9 */
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p0 = 1.666675248e-1f,
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p1 = 7.495297643e-2f,
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p2 = 4.547037598e-2f,
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p3 = 2.417951451e-2f,
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p4 = 4.216630880e-2f;
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float __ieee754_asinf(float x)
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{
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float t,w,p,q,c,r,s;
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int32_t hx,ix;
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GET_FLOAT_WORD(hx,x);
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ix = hx&0x7fffffff;
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if(ix==0x3f800000) {
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/* asin(1)=+-pi/2 with inexact */
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return x*pio2_hi+x*pio2_lo;
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} else if(ix> 0x3f800000) { /* |x|>= 1 */
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return (x-x)/(x-x); /* asin(|x|>1) is NaN */
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} else if (ix<0x3f000000) { /* |x|<0.5 */
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if(ix<0x32000000) { /* if |x| < 2**-27 */
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math_check_force_underflow (x);
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if(huge+x>one) return x;/* return x with inexact if x!=0*/
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} else {
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t = x*x;
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w = t * (p0 + t * (p1 + t * (p2 + t * (p3 + t * p4))));
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return x+x*w;
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}
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}
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/* 1> |x|>= 0.5 */
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w = one-fabsf(x);
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t = w*0.5f;
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p = t * (p0 + t * (p1 + t * (p2 + t * (p3 + t * p4))));
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s = sqrtf(t);
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if(ix>=0x3F79999A) { /* if |x| > 0.975 */
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t = pio2_hi-(2.0f*(s+s*p)-pio2_lo);
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} else {
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int32_t iw;
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w = s;
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GET_FLOAT_WORD(iw,w);
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SET_FLOAT_WORD(w,iw&0xfffff000);
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c = (t-w*w)/(s+w);
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r = p;
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p = 2.0f*s*r-(pio2_lo-2.0f*c);
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q = pio4_hi-2.0f*w;
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t = pio4_hi-(p-q);
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}
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if(hx>0) return t; else return -t;
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}
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libm_alias_finite (__ieee754_asinf, __asinf)
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