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 <sys/cdefs.h> 17 #include "math.h" 18 #include "math_private.h" 19 20 static const float 21 one = 1.0000000000e+00, /* 0x3F800000 */ 22 huge = 1.000e+30, 23 /* coefficient for R(x^2) */ 24 pS0 = 1.6666586697e-01, 25 pS1 = -4.2743422091e-02, 26 pS2 = -8.6563630030e-03, 27 qS1 = -7.0662963390e-01; 28 29 static const double 30 pio2 = 1.570796326794896558e+00; 31 32 float 33 asinf(float x) 34 { 35 double s; 36 float t,w,p,q; 37 int32_t hx,ix; 38 GET_FLOAT_WORD(hx,x); 39 ix = hx&0x7fffffff; 40 if(ix>=0x3f800000) { /* |x| >= 1 */ 41 if(ix==0x3f800000) /* |x| == 1 */ 42 return x*pio2; /* asin(+-1) = +-pi/2 with inexact */ 43 return (x-x)/(x-x); /* asin(|x|>1) is NaN */ 44 } else if (ix<0x3f000000) { /* |x|<0.5 */ 45 if(ix<0x39800000) { /* |x| < 2**-12 */ 46 if(huge+x>one) return x;/* return x with inexact if x!=0*/ 47 } 48 t = x*x; 49 p = t*(pS0+t*(pS1+t*pS2)); 50 q = one+t*qS1; 51 w = p/q; 52 return x+x*w; 53 } 54 /* 1> |x|>= 0.5 */ 55 w = one-fabsf(x); 56 t = w*(float)0.5; 57 p = t*(pS0+t*(pS1+t*pS2)); 58 q = one+t*qS1; 59 s = sqrt(t); 60 w = p/q; 61 t = pio2-2.0*(s+s*w); 62 if(hx>0) return t; else return -t; 63 } 64