12116Sjkh/* s_atanf.c -- float version of s_atan.c. 22116Sjkh * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 32116Sjkh */ 42116Sjkh 52116Sjkh/* 62116Sjkh * ==================================================== 72116Sjkh * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 82116Sjkh * 92116Sjkh * Developed at SunPro, a Sun Microsystems, Inc. business. 102116Sjkh * Permission to use, copy, modify, and distribute this 118870Srgrimes * software is freely granted, provided that this notice 122116Sjkh * is preserved. 132116Sjkh * ==================================================== 142116Sjkh */ 152116Sjkh 16176451Sdas#include <sys/cdefs.h> 17176451Sdas__FBSDID("$FreeBSD$"); 182116Sjkh 192116Sjkh#include "math.h" 202116Sjkh#include "math_private.h" 212116Sjkh 222116Sjkhstatic const float atanhi[] = { 232116Sjkh 4.6364760399e-01, /* atan(0.5)hi 0x3eed6338 */ 242116Sjkh 7.8539812565e-01, /* atan(1.0)hi 0x3f490fda */ 252116Sjkh 9.8279368877e-01, /* atan(1.5)hi 0x3f7b985e */ 262116Sjkh 1.5707962513e+00, /* atan(inf)hi 0x3fc90fda */ 272116Sjkh}; 282116Sjkh 292116Sjkhstatic const float atanlo[] = { 302116Sjkh 5.0121582440e-09, /* atan(0.5)lo 0x31ac3769 */ 312116Sjkh 3.7748947079e-08, /* atan(1.0)lo 0x33222168 */ 322116Sjkh 3.4473217170e-08, /* atan(1.5)lo 0x33140fb4 */ 332116Sjkh 7.5497894159e-08, /* atan(inf)lo 0x33a22168 */ 342116Sjkh}; 352116Sjkh 362116Sjkhstatic const float aT[] = { 37181100Sdas 3.3333328366e-01, 38181100Sdas -1.9999158382e-01, 39181100Sdas 1.4253635705e-01, 40181100Sdas -1.0648017377e-01, 41181100Sdas 6.1687607318e-02, 422116Sjkh}; 432116Sjkh 44181100Sdasstatic const float 452116Sjkhone = 1.0, 462116Sjkhhuge = 1.0e30; 472116Sjkh 4897413Salfredfloat 4997413Salfredatanf(float x) 502116Sjkh{ 512116Sjkh float w,s1,s2,z; 522116Sjkh int32_t ix,hx,id; 532116Sjkh 542116Sjkh GET_FLOAT_WORD(hx,x); 552116Sjkh ix = hx&0x7fffffff; 56181100Sdas if(ix>=0x4c800000) { /* if |x| >= 2**26 */ 572116Sjkh if(ix>0x7f800000) 582116Sjkh return x+x; /* NaN */ 59181062Sdas if(hx>0) return atanhi[3]+*(volatile float *)&atanlo[3]; 60181062Sdas else return -atanhi[3]-*(volatile float *)&atanlo[3]; 612116Sjkh } if (ix < 0x3ee00000) { /* |x| < 0.4375 */ 62181100Sdas if (ix < 0x39800000) { /* |x| < 2**-12 */ 632116Sjkh if(huge+x>one) return x; /* raise inexact */ 642116Sjkh } 652116Sjkh id = -1; 662116Sjkh } else { 672116Sjkh x = fabsf(x); 682116Sjkh if (ix < 0x3f980000) { /* |x| < 1.1875 */ 692116Sjkh if (ix < 0x3f300000) { /* 7/16 <=|x|<11/16 */ 708870Srgrimes id = 0; x = ((float)2.0*x-one)/((float)2.0+x); 712116Sjkh } else { /* 11/16<=|x|< 19/16 */ 728870Srgrimes id = 1; x = (x-one)/(x+one); 732116Sjkh } 742116Sjkh } else { 752116Sjkh if (ix < 0x401c0000) { /* |x| < 2.4375 */ 762116Sjkh id = 2; x = (x-(float)1.5)/(one+(float)1.5*x); 77181100Sdas } else { /* 2.4375 <= |x| < 2**26 */ 782116Sjkh id = 3; x = -(float)1.0/x; 792116Sjkh } 802116Sjkh }} 812116Sjkh /* end of argument reduction */ 822116Sjkh z = x*x; 832116Sjkh w = z*z; 842116Sjkh /* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */ 85181100Sdas s1 = z*(aT[0]+w*(aT[2]+w*aT[4])); 86181100Sdas s2 = w*(aT[1]+w*aT[3]); 872116Sjkh if (id<0) return x - x*(s1+s2); 882116Sjkh else { 892116Sjkh z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x); 902116Sjkh return (hx<0)? -z:z; 912116Sjkh } 922116Sjkh} 93