1 /* e_asinf.c -- float version of e_asin.c. 2 * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. 3 */ 4 5 /* 6 * ==================================================== 7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 8 * 9 * Developed at SunPro, a Sun Microsystems, Inc. business. 10 * Permission to use, copy, modify, and distribute this 11 * software is freely granted, provided that this notice 12 * is preserved. 13 * ==================================================== 14 */ 15 16 #include "cdefs-compat.h" 17 //__FBSDID("$FreeBSD: src/lib/msun/src/e_asinf.c,v 1.13 2008/08/08 00:21:27 das Exp $"); 18 19 #include "openlibm.h" 20 #include "math_private.h" 21 22 static const float 23 one = 1.0000000000e+00, /* 0x3F800000 */ 24 huge = 1.000e+30, 25 /* coefficient for R(x^2) */ 26 pS0 = 1.6666586697e-01, 27 pS1 = -4.2743422091e-02, 28 pS2 = -8.6563630030e-03, 29 qS1 = -7.0662963390e-01; 30 31 static const double 32 pio2 = 1.570796326794896558e+00; 33 34 float 35 __ieee754_asinf(float x) 36 { 37 double s; 38 float t,w,p,q; 39 int32_t hx,ix; 40 GET_FLOAT_WORD(hx,x); 41 ix = hx&0x7fffffff; 42 if(ix>=0x3f800000) { /* |x| >= 1 */ 43 if(ix==0x3f800000) /* |x| == 1 */ 44 return x*pio2; /* asin(+-1) = +-pi/2 with inexact */ 45 return (x-x)/(x-x); /* asin(|x|>1) is NaN */ 46 } else if (ix<0x3f000000) { /* |x|<0.5 */ 47 if(ix<0x39800000) { /* |x| < 2**-12 */ 48 if(huge+x>one) return x;/* return x with inexact if x!=0*/ 49 } 50 t = x*x; 51 p = t*(pS0+t*(pS1+t*pS2)); 52 q = one+t*qS1; 53 w = p/q; 54 return x+x*w; 55 } 56 /* 1> |x|>= 0.5 */ 57 w = one-fabsf(x); 58 t = w*(float)0.5; 59 p = t*(pS0+t*(pS1+t*pS2)); 60 q = one+t*qS1; 61 s = sqrt(t); 62 w = p/q; 63 t = pio2-2.0*(s+s*w); 64 if(hx>0) return t; else return -t; 65 } 66