[cmucl-commit] [git] CMU Common Lisp branch master updated. snapshot-2014-09-9-g128d65b

[Raymond Toy]

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- Log -----------------------------------------------------------------
commit 128d65bef6e7d5c4d2701f05b2944bd5ec2223c9
Author: Raymond Toy <toy.raymond at gmail.com>
Date:   Sat Sep 20 12:51:45 2014 -0700

    Import e_log10.c from netlib as is.

diff --git a/src/lisp/e_log10.c b/src/lisp/e_log10.c
new file mode 100644
index 0000000..dc7e312
--- /dev/null
+++ b/src/lisp/e_log10.c
@@ -0,0 +1,91 @@
+
+/* @(#)e_log10.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.
+ * ====================================================
+ */
+
+/* __ieee754_log10(x)
+ * Return the base 10 logarithm of x
+ * 
+ * Method :
+ *	Let log10_2hi = leading 40 bits of log10(2) and
+ *	    log10_2lo = log10(2) - log10_2hi,
+ *	    ivln10   = 1/log(10) rounded.
+ *	Then
+ *		n = ilogb(x), 
+ *		if(n<0)  n = n+1;
+ *		x = scalbn(x,-n);
+ *		log10(x) := n*log10_2hi + (n*log10_2lo + ivln10*log(x))
+ *
+ * Note 1:
+ *	To guarantee log10(10**n)=n, where 10**n is normal, the rounding 
+ *	mode must set to Round-to-Nearest.
+ * Note 2:
+ *	[1/log(10)] rounded to 53 bits has error  .198   ulps;
+ *	log10 is monotonic at all binary break points.
+ *
+ * Special cases:
+ *	log10(x) is NaN with signal if x < 0; 
+ *	log10(+INF) is +INF with no signal; log10(0) is -INF with signal;
+ *	log10(NaN) is that NaN with no signal;
+ *	log10(10**N) = N  for N=0,1,...,22.
+ *
+ * Constants:
+ * The hexadecimal values are the intended ones for the following constants.
+ * The decimal values may be used, provided that the compiler will convert
+ * from decimal to binary accurately enough to produce the hexadecimal values
+ * shown.
+ */
+
+#include "fdlibm.h"
+
+#ifdef __STDC__
+static const double
+#else
+static double
+#endif
+two54      =  1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
+ivln10     =  4.34294481903251816668e-01, /* 0x3FDBCB7B, 0x1526E50E */
+log10_2hi  =  3.01029995663611771306e-01, /* 0x3FD34413, 0x509F6000 */
+log10_2lo  =  3.69423907715893078616e-13; /* 0x3D59FEF3, 0x11F12B36 */
+
+static double zero   =  0.0;
+
+#ifdef __STDC__
+	double __ieee754_log10(double x)
+#else
+	double __ieee754_log10(x)
+	double x;
+#endif
+{
+	double y,z;
+	int i,k,hx;
+	unsigned lx;
+
+	hx = __HI(x);	/* high word of x */
+	lx = __LO(x);	/* low word of x */
+
+        k=0;
+        if (hx < 0x00100000) {                  /* x < 2**-1022  */
+            if (((hx&0x7fffffff)|lx)==0)
+                return -two54/zero;             /* log(+-0)=-inf */
+            if (hx<0) return (x-x)/zero;        /* log(-#) = NaN */
+            k -= 54; x *= two54; /* subnormal number, scale up x */
+            hx = __HI(x);                /* high word of x */
+        }
+	if (hx >= 0x7ff00000) return x+x;
+	k += (hx>>20)-1023;
+	i  = ((unsigned)k&0x80000000)>>31;
+        hx = (hx&0x000fffff)|((0x3ff-i)<<20);
+        y  = (double)(k+i);
+        __HI(x) = hx;
+	z  = y*log10_2lo + ivln10*__ieee754_log(x);
+	return  z+y*log10_2hi;
+}

-----------------------------------------------------------------------

Summary of changes:
 src/lisp/e_log10.c |   91 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 src/lisp/e_log10.c


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