e_asinf.c revision 181405
1254721Semaste/* e_asinf.c -- float version of e_asin.c. 2254721Semaste * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3254721Semaste */ 4254721Semaste 5254721Semaste/* 6254721Semaste * ==================================================== 7254721Semaste * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8254721Semaste * 9254721Semaste * Developed at SunPro, a Sun Microsystems, Inc. business. 10254721Semaste * Permission to use, copy, modify, and distribute this 11254721Semaste * software is freely granted, provided that this notice 12254721Semaste * is preserved. 13254721Semaste * ==================================================== 14254721Semaste */ 15254721Semaste 16254721Semaste#include <sys/cdefs.h> 17254721Semaste__FBSDID("$FreeBSD: head/lib/msun/src/e_asinf.c 181405 2008-08-08 00:21:27Z das $"); 18254721Semaste 19254721Semaste#include "math.h" 20254721Semaste#include "math_private.h" 21254721Semaste 22254721Semastestatic const float 23254721Semasteone = 1.0000000000e+00, /* 0x3F800000 */ 24254721Semastehuge = 1.000e+30, 25254721Semaste /* coefficient for R(x^2) */ 26254721SemastepS0 = 1.6666586697e-01, 27254721SemastepS1 = -4.2743422091e-02, 28254721SemastepS2 = -8.6563630030e-03, 29254721SemasteqS1 = -7.0662963390e-01; 30254721Semaste 31254721Semastestatic const double 32254721Semastepio2 = 1.570796326794896558e+00; 33254721Semaste 34254721Semastefloat 35254721Semaste__ieee754_asinf(float x) 36254721Semaste{ 37254721Semaste double s; 38254721Semaste float t,w,p,q; 39254721Semaste int32_t hx,ix; 40254721Semaste GET_FLOAT_WORD(hx,x); 41254721Semaste ix = hx&0x7fffffff; 42254721Semaste if(ix>=0x3f800000) { /* |x| >= 1 */ 43254721Semaste if(ix==0x3f800000) /* |x| == 1 */ 44254721Semaste return x*pio2; /* asin(+-1) = +-pi/2 with inexact */ 45254721Semaste return (x-x)/(x-x); /* asin(|x|>1) is NaN */ 46254721Semaste } else if (ix<0x3f000000) { /* |x|<0.5 */ 47254721Semaste if(ix<0x39800000) { /* |x| < 2**-12 */ 48254721Semaste if(huge+x>one) return x;/* return x with inexact if x!=0*/ 49254721Semaste } 50254721Semaste t = x*x; 51254721Semaste p = t*(pS0+t*(pS1+t*pS2)); 52254721Semaste q = one+t*qS1; 53254721Semaste w = p/q; 54254721Semaste return x+x*w; 55254721Semaste } 56254721Semaste /* 1> |x|>= 0.5 */ 57254721Semaste w = one-fabsf(x); 58254721Semaste t = w*(float)0.5; 59254721Semaste p = t*(pS0+t*(pS1+t*pS2)); 60254721Semaste q = one+t*qS1; 61254721Semaste s = sqrt(t); 62254721Semaste w = p/q; 63254721Semaste t = pio2-2.0*(s+s*w); 64254721Semaste if(hx>0) return t; else return -t; 65254721Semaste} 66254721Semaste