9b7ee67e0c
2001-04-16 Stephen L Moshier <moshier@mediaone.net> * sysdeps/ieee754/flt-32/e_asinf.c (pio2_hi, pio2_lo, pio4_hi): Correct the values. (pSx, qSx): Replace by shorter approximation. Use f suffix on float constants. * sysdeps/ieee754/ldbl-128/k_tanl.c: New file. Contributed by Stephen L Moshier <moshier@mediaone.net>.
95 lines
2.3 KiB
C
95 lines
2.3 KiB
C
/* e_asinf.c -- float version of e_asin.c.
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* Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
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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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Single precision expansion contributed by
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Stephen L. Moshier <moshier@na-net.ornl.gov>
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*/
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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 "math.h"
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#include "math_private.h"
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#ifdef __STDC__
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static const float
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#else
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static float
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#endif
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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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#ifdef __STDC__
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float __ieee754_asinf(float x)
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#else
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float __ieee754_asinf(x)
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float x;
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#endif
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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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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 = __ieee754_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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