e_asinf.c revision 8870 
12116Sjkh/* e_asinf.c -- float version of e_asin.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
162116Sjkh#ifndef lint
178870Srgrimesstatic char rcsid[] = "$Id: e_asinf.c,v 1.1.1.1 1994/08/19 09:39:44 jkh Exp $";
182116Sjkh#endif
192116Sjkh
202116Sjkh#include "math.h"
212116Sjkh#include "math_private.h"
222116Sjkh
232116Sjkh#ifdef __STDC__
248870Srgrimesstatic const float
252116Sjkh#else
268870Srgrimesstatic float
272116Sjkh#endif
282116Sjkhone =  1.0000000000e+00, /* 0x3F800000 */
292116Sjkhhuge =  1.000e+30,
302116Sjkhpio2_hi =  1.5707962513e+00, /* 0x3fc90fda */
312116Sjkhpio2_lo =  7.5497894159e-08, /* 0x33a22168 */
322116Sjkhpio4_hi =  7.8539818525e-01, /* 0x3f490fdb */
332116Sjkh	/* coefficient for R(x^2) */
342116SjkhpS0 =  1.6666667163e-01, /* 0x3e2aaaab */
352116SjkhpS1 = -3.2556581497e-01, /* 0xbea6b090 */
362116SjkhpS2 =  2.0121252537e-01, /* 0x3e4e0aa8 */
372116SjkhpS3 = -4.0055535734e-02, /* 0xbd241146 */
382116SjkhpS4 =  7.9153501429e-04, /* 0x3a4f7f04 */
392116SjkhpS5 =  3.4793309169e-05, /* 0x3811ef08 */
402116SjkhqS1 = -2.4033949375e+00, /* 0xc019d139 */
412116SjkhqS2 =  2.0209457874e+00, /* 0x4001572d */
422116SjkhqS3 = -6.8828397989e-01, /* 0xbf303361 */
432116SjkhqS4 =  7.7038154006e-02; /* 0x3d9dc62e */
442116Sjkh
452116Sjkh#ifdef __STDC__
462116Sjkh	float __ieee754_asinf(float x)
472116Sjkh#else
482116Sjkh	float __ieee754_asinf(x)
492116Sjkh	float x;
502116Sjkh#endif
512116Sjkh{
522116Sjkh	float t,w,p,q,c,r,s;
532116Sjkh	int32_t hx,ix;
542116Sjkh	GET_FLOAT_WORD(hx,x);
552116Sjkh	ix = hx&0x7fffffff;
562116Sjkh	if(ix==0x3f800000) {
572116Sjkh		/* asin(1)=+-pi/2 with inexact */
588870Srgrimes	    return x*pio2_hi+x*pio2_lo;
592116Sjkh	} else if(ix> 0x3f800000) {	/* |x|>= 1 */
608870Srgrimes	    return (x-x)/(x-x);		/* asin(|x|>1) is NaN */
612116Sjkh	} else if (ix<0x3f000000) {	/* |x|<0.5 */
622116Sjkh	    if(ix<0x32000000) {		/* if |x| < 2**-27 */
632116Sjkh		if(huge+x>one) return x;/* return x with inexact if x!=0*/
648870Srgrimes	    } else
652116Sjkh		t = x*x;
662116Sjkh		p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
672116Sjkh		q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
682116Sjkh		w = p/q;
692116Sjkh		return x+x*w;
702116Sjkh	}
712116Sjkh	/* 1> |x|>= 0.5 */
722116Sjkh	w = one-fabsf(x);
732116Sjkh	t = w*(float)0.5;
742116Sjkh	p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
752116Sjkh	q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
762116Sjkh	s = sqrtf(t);
772116Sjkh	if(ix>=0x3F79999A) { 	/* if |x| > 0.975 */
782116Sjkh	    w = p/q;
792116Sjkh	    t = pio2_hi-((float)2.0*(s+s*w)-pio2_lo);
802116Sjkh	} else {
812116Sjkh	    int32_t iw;
822116Sjkh	    w  = s;
832116Sjkh	    GET_FLOAT_WORD(iw,w);
842116Sjkh	    SET_FLOAT_WORD(w,iw&0xfffff000);
852116Sjkh	    c  = (t-w*w)/(s+w);
862116Sjkh	    r  = p/q;
872116Sjkh	    p  = (float)2.0*s*r-(pio2_lo-(float)2.0*c);
882116Sjkh	    q  = pio4_hi-(float)2.0*w;
892116Sjkh	    t  = pio4_hi-(p-q);
908870Srgrimes	}
918870Srgrimes	if(hx>0) return t; else return -t;
922116Sjkh}
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