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authorThe Android Open Source Project <initial-contribution@android.com>2009-03-03 19:28:35 -0800
committerThe Android Open Source Project <initial-contribution@android.com>2009-03-03 19:28:35 -0800
commit1dc9e472e19acfe6dc7f41e429236e7eef7ceda1 (patch)
tree3be0c520fae17689bbf5584e1136fb820caef26f /libm/src/e_asinf.c
parent1767f908af327fa388b1c66883760ad851267013 (diff)
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+/* e_asinf.c -- float version of e_asin.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#ifndef lint
+static char rcsid[] = "$FreeBSD: src/lib/msun/src/e_asinf.c,v 1.9 2005/12/04 13:52:46 bde Exp $";
+#endif
+
+#include "math.h"
+#include "math_private.h"
+
+static const float
+one = 1.0000000000e+00, /* 0x3F800000 */
+huge = 1.000e+30,
+pio2_hi = 1.5707962513e+00, /* 0x3fc90fda */
+pio2_lo = 7.5497894159e-08, /* 0x33a22168 */
+pio4_hi = 7.8539812565e-01, /* 0x3f490fda */
+ /* coefficient for R(x^2) */
+pS0 = 1.6666667163e-01, /* 0x3e2aaaab */
+pS1 = -3.2556581497e-01, /* 0xbea6b090 */
+pS2 = 2.0121252537e-01, /* 0x3e4e0aa8 */
+pS3 = -4.0055535734e-02, /* 0xbd241146 */
+pS4 = 7.9153501429e-04, /* 0x3a4f7f04 */
+pS5 = 3.4793309169e-05, /* 0x3811ef08 */
+qS1 = -2.4033949375e+00, /* 0xc019d139 */
+qS2 = 2.0209457874e+00, /* 0x4001572d */
+qS3 = -6.8828397989e-01, /* 0xbf303361 */
+qS4 = 7.7038154006e-02; /* 0x3d9dc62e */
+
+float
+__ieee754_asinf(float x)
+{
+ float t=0.0,w,p,q,c,r,s;
+ int32_t hx,ix;
+ GET_FLOAT_WORD(hx,x);
+ ix = hx&0x7fffffff;
+ if(ix==0x3f800000) {
+ /* asin(1)=+-pi/2 with inexact */
+ return x*pio2_hi+x*pio2_lo;
+ } else if(ix> 0x3f800000) { /* |x|>= 1 */
+ return (x-x)/(x-x); /* asin(|x|>1) is NaN */
+ } else if (ix<0x3f000000) { /* |x|<0.5 */
+ if(ix<0x32000000) { /* if |x| < 2**-27 */
+ if(huge+x>one) return x;/* return x with inexact if x!=0*/
+ } else
+ t = x*x;
+ p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
+ q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
+ w = p/q;
+ return x+x*w;
+ }
+ /* 1> |x|>= 0.5 */
+ w = one-fabsf(x);
+ t = w*(float)0.5;
+ p = t*(pS0+t*(pS1+t*(pS2+t*(pS3+t*(pS4+t*pS5)))));
+ q = one+t*(qS1+t*(qS2+t*(qS3+t*qS4)));
+ s = __ieee754_sqrtf(t);
+ if(ix>=0x3F79999A) { /* if |x| > 0.975 */
+ w = p/q;
+ t = pio2_hi-((float)2.0*(s+s*w)-pio2_lo);
+ } else {
+ int32_t iw;
+ w = s;
+ GET_FLOAT_WORD(iw,w);
+ SET_FLOAT_WORD(w,iw&0xfffff000);
+ c = (t-w*w)/(s+w);
+ r = p/q;
+ p = (float)2.0*s*r-(pio2_lo-(float)2.0*c);
+ q = pio4_hi-(float)2.0*w;
+ t = pio4_hi-(p-q);
+ }
+ if(hx>0) return t; else return -t;
+}