e_acosf.c revision 2116
11558Srgrimes/* e_acosf.c -- float version of e_acos.c. 21558Srgrimes * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 31558Srgrimes */ 41558Srgrimes 51558Srgrimes/* 61558Srgrimes * ==================================================== 71558Srgrimes * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 81558Srgrimes * 91558Srgrimes * Developed at SunPro, a Sun Microsystems, Inc. business. 101558Srgrimes * Permission to use, copy, modify, and distribute this 111558Srgrimes * software is freely granted, provided that this notice 121558Srgrimes * is preserved. 131558Srgrimes * ==================================================== 141558Srgrimes */ 151558Srgrimes 161558Srgrimes#ifndef lint 171558Srgrimesstatic char rcsid[] = "$Id: e_acosf.c,v 1.2 1994/08/18 23:04:53 jtc Exp $"; 181558Srgrimes#endif 191558Srgrimes 201558Srgrimes#include "math.h" 211558Srgrimes#include "math_private.h" 221558Srgrimes 231558Srgrimes#ifdef __STDC__ 241558Srgrimesstatic const float 251558Srgrimes#else 261558Srgrimesstatic float 271558Srgrimes#endif 281558Srgrimesone = 1.0000000000e+00, /* 0x3F800000 */ 291558Srgrimespi = 3.1415925026e+00, /* 0x40490fda */ 301558Srgrimespio2_hi = 1.5707962513e+00, /* 0x3fc90fda */ 311558Srgrimespio2_lo = 7.5497894159e-08, /* 0x33a22168 */ 321558SrgrimespS0 = 1.6666667163e-01, /* 0x3e2aaaab */ 331558SrgrimespS1 = -3.2556581497e-01, /* 0xbea6b090 */ 341558SrgrimespS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */ 351558SrgrimespS3 = -4.0055535734e-02, /* 0xbd241146 */ 3637906ScharnierpS4 = 7.9153501429e-04, /* 0x3a4f7f04 */ 3723685SpeterpS5 = 3.4793309169e-05, /* 0x3811ef08 */ 3837906ScharnierqS1 = -2.4033949375e+00, /* 0xc019d139 */ 391558SrgrimesqS2 = 2.0209457874e+00, /* 0x4001572d */ 401558SrgrimesqS3 = -6.8828397989e-01, /* 0xbf303361 */ 41146754ScharnierqS4 = 7.7038154006e-02; /* 0x3d9dc62e */ 42146754Scharnier 43146754Scharnier#ifdef __STDC__ 441558Srgrimes float __ieee754_acosf(float x) 451558Srgrimes#else 461558Srgrimes float __ieee754_acosf(x) 471558Srgrimes float x; 4866907Swollman#endif 49167011Smckusick{ 50167011Smckusick float z,p,q,r,w,s,c,df; 511558Srgrimes int32_t hx,ix; 52167259Smckusick GET_FLOAT_WORD(hx,x); 531558Srgrimes ix = hx&0x7fffffff; 541558Srgrimes if(ix==0x3f800000) { /* |x|==1 */ 551558Srgrimes if(hx>0) return 0.0; /* acos(1) = 0 */ 561558Srgrimes else return pi+(float)2.0*pio2_lo; /* acos(-1)= pi */ 57103949Smike } else if(ix>0x3f800000) { /* |x| >= 1 */ 5873986Sobrien return (x-x)/(x-x); /* acos(|x|>1) is NaN */ 591558Srgrimes } 60164911Sdwmalone if(ix<0x3f000000) { /* |x| < 0.5 */ 611558Srgrimes if(ix<=0x23000000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/ 621558Srgrimes z = x*x; 631558Srgrimes p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); 6466907Swollman q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); 65129665Sstefanf r = p/q; 661558Srgrimes return pio2_hi - (x - (pio2_lo-x*r)); 671558Srgrimes } else if (hx<0) { /* x < -0.5 */ 681558Srgrimes z = (one+x)*(float)0.5; 691558Srgrimes p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); 701558Srgrimes q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); 711558Srgrimes s = sqrtf(z); 721558Srgrimes r = p/q; 731558Srgrimes w = r*s-pio2_lo; 74128175Sgreen return pi - (float)2.0*(s+w); 75128175Sgreen } else { /* x > 0.5 */ 7621174Sguido int32_t idf; 771558Srgrimes z = (one-x)*(float)0.5; 781558Srgrimes s = sqrtf(z); 791558Srgrimes df = s; 801558Srgrimes GET_FLOAT_WORD(idf,df); 81164911Sdwmalone SET_FLOAT_WORD(df,idf&0xfffff000); 821558Srgrimes c = (z-df*df)/(s+df); 8398542Smckusick p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5))))); 841558Srgrimes q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4))); 851558Srgrimes r = p/q; 861558Srgrimes w = r*s+c; 871558Srgrimes return (float)2.0*(df+w); 8898542Smckusick } 891558Srgrimes} 901558Srgrimes