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 diff --git a/src/math/e_acos.c b/src/math/e_acos.cnew file mode 100644index 00000000..e0236391--- /dev/null+++ b/src/math/e_acos.c@@ -0,0 +1,99 @@+/* @(#)e_acos.c 1.3 95/01/18 */+/*+ * ====================================================+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.+ *+ * Developed at SunSoft, a Sun Microsystems, Inc. business.+ * Permission to use, copy, modify, and distribute this+ * software is freely granted, provided that this notice + * is preserved.+ * ====================================================+ */++/* acos(x)+ * Method : + * acos(x) = pi/2 - asin(x)+ * acos(-x) = pi/2 + asin(x)+ * For |x|<=0.5+ * acos(x) = pi/2 - (x + x*x^2*R(x^2)) (see asin.c)+ * For x>0.5+ * acos(x) = pi/2 - (pi/2 - 2asin(sqrt((1-x)/2)))+ * = 2asin(sqrt((1-x)/2)) + * = 2s + 2s*z*R(z) ...z=(1-x)/2, s=sqrt(z)+ * = 2f + (2c + 2s*z*R(z))+ * where f=hi part of s, and c = (z-f*f)/(s+f) is the correction term+ * for f so that f+c ~ sqrt(z).+ * For x<-0.5+ * acos(x) = pi - 2asin(sqrt((1-|x|)/2))+ * = pi - 0.5*(s+s*z*R(z)), where z=(1-|x|)/2,s=sqrt(z)+ *+ * Special cases:+ * if x is NaN, return x itself;+ * if |x|>1, return NaN with invalid signal.+ *+ * Function needed: sqrt+ */++#include +#include "math_private.h"++static const double+one= 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */+pi = 3.14159265358979311600e+00, /* 0x400921FB, 0x54442D18 */+pio2_hi = 1.57079632679489655800e+00, /* 0x3FF921FB, 0x54442D18 */+pio2_lo = 6.12323399573676603587e-17, /* 0x3C91A626, 0x33145C07 */+pS0 = 1.66666666666666657415e-01, /* 0x3FC55555, 0x55555555 */+pS1 = -3.25565818622400915405e-01, /* 0xBFD4D612, 0x03EB6F7D */+pS2 = 2.01212532134862925881e-01, /* 0x3FC9C155, 0x0E884455 */+pS3 = -4.00555345006794114027e-02, /* 0xBFA48228, 0xB5688F3B */+pS4 = 7.91534994289814532176e-04, /* 0x3F49EFE0, 0x7501B288 */+pS5 = 3.47933107596021167570e-05, /* 0x3F023DE1, 0x0DFDF709 */+qS1 = -2.40339491173441421878e+00, /* 0xC0033A27, 0x1C8A2D4B */+qS2 = 2.02094576023350569471e+00, /* 0x40002AE5, 0x9C598AC8 */+qS3 = -6.88283971605453293030e-01, /* 0xBFE6066C, 0x1B8D0159 */+qS4 = 7.70381505559019352791e-02; /* 0x3FB3B8C5, 0xB12E9282 */++double+acos(double x)+{+ double z,p,q,r,w,s,c,df;+ int32_t hx,ix;+ GET_HIGH_WORD(hx,x);+ ix = hx&0x7fffffff;+ if(ix>=0x3ff00000) { /* |x| >= 1 */+ uint32_t lx;+ GET_LOW_WORD(lx,x);+ if(((ix-0x3ff00000)|lx)==0) { /* |x|==1 */+ if(hx>0) return 0.0; /* acos(1) = 0 */+ else return pi+2.0*pio2_lo; /* acos(-1)= pi */+ }+ return (x-x)/(x-x); /* acos(|x|>1) is NaN */+ }+ if(ix<0x3fe00000) { /* |x| < 0.5 */+ if(ix<=0x3c600000) return pio2_hi+pio2_lo;/*if|x|<2**-57*/+ z = x*x;+ p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));+ q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));+ r = p/q;+ return pio2_hi - (x - (pio2_lo-x*r));+ } else if (hx<0) { /* x < -0.5 */+ z = (one+x)*0.5;+ p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));+ q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));+ s = sqrt(z);+ r = p/q;+ w = r*s-pio2_lo;+ return pi - 2.0*(s+w);+ } else { /* x > 0.5 */+ z = (one-x)*0.5;+ s = sqrt(z);+ df = s;+ SET_LOW_WORD(df,0);+ c = (z-df*df)/(s+df);+ p = z*(pS0+z*(pS1+z*(pS2+z*(pS3+z*(pS4+z*pS5)))));+ q = one+z*(qS1+z*(qS2+z*(qS3+z*qS4)));+ r = p/q;+ w = r*s+c;+ return 2.0*(df+w);+ }+}