Initial Contributionandroid-1.0

1 files changed, 177 insertions, 0 deletions

diff --git a/libm/bsdsrc/b_exp.c b/libm/bsdsrc/b_exp.c
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+/*
+ * Copyright (c) 1985, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)exp.c	8.1 (Berkeley) 6/4/93";
+#endif /* not lint */
+#include <sys/cdefs.h>
+/* __FBSDID("$FreeBSD: src/lib/msun/bsdsrc/b_exp.c,v 1.7 2004/12/16 20:40:37 das Exp $"); */
+
+
+/* EXP(X)
+ * RETURN THE EXPONENTIAL OF X
+ * DOUBLE PRECISION (IEEE 53 bits, VAX D FORMAT 56 BITS)
+ * CODED IN C BY K.C. NG, 1/19/85;
+ * REVISED BY K.C. NG on 2/6/85, 2/15/85, 3/7/85, 3/24/85, 4/16/85, 6/14/86.
+ *
+ * Required system supported functions:
+ *	scalb(x,n)
+ *	copysign(x,y)
+ *	finite(x)
+ *
+ * Method:
+ *	1. Argument Reduction: given the input x, find r and integer k such
+ *	   that
+ *	                   x = k*ln2 + r,  |r| <= 0.5*ln2 .
+ *	   r will be represented as r := z+c for better accuracy.
+ *
+ *	2. Compute exp(r) by
+ *
+ *		exp(r) = 1 + r + r*R1/(2-R1),
+ *	   where
+ *		R1 = x - x^2*(p1+x^2*(p2+x^2*(p3+x^2*(p4+p5*x^2)))).
+ *
+ *	3. exp(x) = 2^k * exp(r) .
+ *
+ * Special cases:
+ *	exp(INF) is INF, exp(NaN) is NaN;
+ *	exp(-INF)=  0;
+ *	for finite argument, only exp(0)=1 is exact.
+ *
+ * Accuracy:
+ *	exp(x) returns the exponential of x nearly rounded. In a test run
+ *	with 1,156,000 random arguments on a VAX, the maximum observed
+ *	error was 0.869 ulps (units in the last place).
+ */
+
+#include "mathimpl.h"
+
+const static double p1 = 0x1.555555555553ep-3;
+const static double p2 = -0x1.6c16c16bebd93p-9;
+const static double p3 = 0x1.1566aaf25de2cp-14;
+const static double p4 = -0x1.bbd41c5d26bf1p-20;
+const static double p5 = 0x1.6376972bea4d0p-25;
+const static double ln2hi = 0x1.62e42fee00000p-1;
+const static double ln2lo = 0x1.a39ef35793c76p-33;
+const static double lnhuge = 0x1.6602b15b7ecf2p9;
+const static double lntiny = -0x1.77af8ebeae354p9;
+const static double invln2 = 0x1.71547652b82fep0;
+
+#if 0
+double exp(x)
+double x;
+{
+	double  z,hi,lo,c;
+	int k;
+
+#if !defined(vax)&&!defined(tahoe)
+	if(x!=x) return(x);	/* x is NaN */
+#endif	/* !defined(vax)&&!defined(tahoe) */
+	if( x <= lnhuge ) {
+		if( x >= lntiny ) {
+
+		    /* argument reduction : x --> x - k*ln2 */
+
+			k=invln2*x+copysign(0.5,x);	/* k=NINT(x/ln2) */
+
+		    /* express x-k*ln2 as hi-lo and let x=hi-lo rounded */
+
+			hi=x-k*ln2hi;
+			x=hi-(lo=k*ln2lo);
+
+		    /* return 2^k*[1+x+x*c/(2+c)]  */
+			z=x*x;
+			c= x - z*(p1+z*(p2+z*(p3+z*(p4+z*p5))));
+			return  scalb(1.0+(hi-(lo-(x*c)/(2.0-c))),k);
+
+		}
+		/* end of x > lntiny */
+
+		else
+		     /* exp(-big#) underflows to zero */
+		     if(finite(x))  return(scalb(1.0,-5000));
+
+		     /* exp(-INF) is zero */
+		     else return(0.0);
+	}
+	/* end of x < lnhuge */
+
+	else
+	/* exp(INF) is INF, exp(+big#) overflows to INF */
+	    return( finite(x) ?  scalb(1.0,5000)  : x);
+}
+#endif
+
+/* returns exp(r = x + c) for |c| < |x| with no overlap.  */
+
+double __exp__D(x, c)
+double x, c;
+{
+	double  z,hi,lo;
+	int k;
+
+	if (x != x)	/* x is NaN */
+		return(x);
+	if ( x <= lnhuge ) {
+		if ( x >= lntiny ) {
+
+		    /* argument reduction : x --> x - k*ln2 */
+			z = invln2*x;
+			k = z + copysign(.5, x);
+
+		    /* express (x+c)-k*ln2 as hi-lo and let x=hi-lo rounded */
+
+			hi=(x-k*ln2hi);			/* Exact. */
+			x= hi - (lo = k*ln2lo-c);
+		    /* return 2^k*[1+x+x*c/(2+c)]  */
+			z=x*x;
+			c= x - z*(p1+z*(p2+z*(p3+z*(p4+z*p5))));
+			c = (x*c)/(2.0-c);
+
+			return  scalb(1.+(hi-(lo - c)), k);
+		}
+		/* end of x > lntiny */
+
+		else
+		     /* exp(-big#) underflows to zero */
+		     if(finite(x))  return(scalb(1.0,-5000));
+
+		     /* exp(-INF) is zero */
+		     else return(0.0);
+	}
+	/* end of x < lnhuge */
+
+	else
+	/* exp(INF) is INF, exp(+big#) overflows to INF */
+	    return( finite(x) ?  scalb(1.0,5000)  : x);
+}