From 0b44a0315b47dd8eced9f3b7f31580cf14bbfc01 Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Sat, 12 Feb 2011 00:22:29 -0500
Subject: initial check-in, version 0.5.0

---
 src/math/e_acosf.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 src/math/e_acosf.c

(limited to 'src/math/e_acosf.c')

diff --git a/src/math/e_acosf.c b/src/math/e_acosf.c
new file mode 100644
index 00000000..4c59781b
--- /dev/null
+++ b/src/math/e_acosf.c
@@ -0,0 +1,77 @@
+/* e_acosf.c -- float version of e_acos.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.
+ * ====================================================
+ */
+
+#include <math.h>
+#include "math_private.h"
+
+static const float
+one =  1.0000000000e+00, /* 0x3F800000 */
+pi =  3.1415925026e+00, /* 0x40490fda */
+pio2_hi =  1.5707962513e+00, /* 0x3fc90fda */
+pio2_lo =  7.5497894159e-08, /* 0x33a22168 */
+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
+acosf(float x)
+{
+        float z,p,q,r,w,s,c,df;
+        int32_t hx,ix;
+        GET_FLOAT_WORD(hx,x);
+        ix = hx&0x7fffffff;
+        if(ix==0x3f800000) {            /* |x|==1 */
+            if(hx>0) return 0.0;        /* acos(1) = 0  */
+            else return pi+(float)2.0*pio2_lo;  /* acos(-1)= pi */
+        } else if(ix>0x3f800000) {      /* |x| >= 1 */
+            return (x-x)/(x-x);         /* acos(|x|>1) is NaN */
+        }
+        if(ix<0x3f000000) {     /* |x| < 0.5 */
+            if(ix<=0x23000000) 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)*(float)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 = sqrtf(z);
+            r = p/q;
+            w = r*s-pio2_lo;
+            return pi - (float)2.0*(s+w);
+        } else {                        /* x > 0.5 */
+            int32_t idf;
+            z = (one-x)*(float)0.5;
+            s = sqrtf(z);
+            df = s;
+            GET_FLOAT_WORD(idf,df);
+            SET_FLOAT_WORD(df,idf&0xfffff000);
+            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 (float)2.0*(df+w);
+        }
+}
-- 
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