diff --git a/src/lib/math/log.go b/src/lib/math/log.go
index e51c729..c0cfebf 100644
--- a/src/lib/math/log.go
+++ b/src/lib/math/log.go
@@ -4,56 +4,128 @@
 
 package math
 
-/*
- *	Log returns the natural logarithm of its floating
- *	point argument.
- *
- *	The coefficients are #2705 from Hart & Cheney. (19.38D)
- *
- *	It calls frexp.
- */
+// The original C code, the long comment, and the constants
+// below are from FreeBSD's /usr/src/lib/msun/src/e_log.c
+// and came with this notice.  The go code is a simpler
+// version of the original C.
+//
+// ====================================================
+// 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.
+// ====================================================
+//
+// __ieee754_log(x)
+// Return the logrithm of x
+//
+// Method :
+//   1. Argument Reduction: find k and f such that
+//			x = 2^k * (1+f),
+//	   where  sqrt(2)/2 < 1+f < sqrt(2) .
+//
+//   2. Approximation of log(1+f).
+//	Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s)
+//		 = 2s + 2/3 s**3 + 2/5 s**5 + .....,
+//	     	 = 2s + s*R
+//      We use a special Reme algorithm on [0,0.1716] to generate
+// 	a polynomial of degree 14 to approximate R The maximum error
+//	of this polynomial approximation is bounded by 2**-58.45. In
+//	other words,
+//		        2      4      6      8      10      12      14
+//	    R(z) ~ Lg1*s +Lg2*s +Lg3*s +Lg4*s +Lg5*s  +Lg6*s  +Lg7*s
+//  	(the values of Lg1 to Lg7 are listed in the program)
+//	and
+//	    |      2          14          |     -58.45
+//	    | Lg1*s +...+Lg7*s    -  R(z) | <= 2
+//	    |                             |
+//	Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2.
+//	In order to guarantee error in log below 1ulp, we compute log
+//	by
+//		log(1+f) = f - s*(f - R)	(if f is not too large)
+//		log(1+f) = f - (hfsq - s*(hfsq+R)).	(better accuracy)
+//
+//	3. Finally,  log(x) = k*ln2 + log(1+f).
+//			    = k*ln2_hi+(f-(hfsq-(s*(hfsq+R)+k*ln2_lo)))
+//	   Here ln2 is split into two floating point number:
+//			ln2_hi + ln2_lo,
+//	   where n*ln2_hi is always exact for |n| < 2000.
+//
+// Special cases:
+//	log(x) is NaN with signal if x < 0 (including -INF) ;
+//	log(+INF) is +INF; log(0) is -INF with signal;
+//	log(NaN) is that NaN with no signal.
+//
+// Accuracy:
+//	according to an error analysis, the error is always less than
+//	1 ulp (unit in the last place).
+//
+// 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.
+
+const (
+	Ln2Hi = 6.93147180369123816490e-01;	/* 3fe62e42 fee00000 */
+	Ln2Lo = 1.90821492927058770002e-10;	/* 3dea39ef 35793c76 */
+	Lg1 = 6.666666666666735130e-01;  /* 3FE55555 55555593 */
+	Lg2 = 3.999999999940941908e-01;  /* 3FD99999 9997FA04 */
+	Lg3 = 2.857142874366239149e-01;  /* 3FD24924 94229359 */
+	Lg4 = 2.222219843214978396e-01;  /* 3FCC71C5 1D8E78AF */
+	Lg5 = 1.818357216161805012e-01;  /* 3FC74664 96CB03DE */
+	Lg6 = 1.531383769920937332e-01;  /* 3FC39A09 D078C69F */
+	Lg7 = 1.479819860511658591e-01;  /* 3FC2F112 DF3E5244 */
+
+	Two54 = 1<<54;				// 2^54
+	TwoM20 = 1.0/(1<<20);		// 2^-20
+	TwoM1022 = 2.2250738585072014e-308;	// 2^-1022
+	Sqrt2 = 1.41421356237309504880168872420969808;
+)
+
+export func Log(x float64) float64 {
+	// special cases
+	switch {
+	case sys.isNaN(x) || sys.isInf(x, 1):
+		return x;
+	case x < 0:
+		return sys.NaN();
+	case x == 0:
+		return sys.Inf(-1);
+	}
+
+	// reduce
+	f1, ki := sys.frexp(x);
+	if f1 < Sqrt2/2 {
+		f1 *= 2;
+		ki--;
+	}
+	f := f1 - 1;
+	k := float64(ki);
+
+	// compute
+	s := f/(2+f);
+	s2 := s*s;
+	s4 := s2*s2;
+	t1 := s2*(Lg1 + s4*(Lg3 + s4*(Lg5 + s4*Lg7)));
+	t2 := s4*(Lg2 + s4*(Lg4 + s4*Lg6));
+	R :=  t1 + t2;
+	hfsq := 0.5*f*f;
+	return k*Ln2Hi - ((hfsq-(s*(hfsq+R)+k*Ln2Lo)) - f);
+}
 
 const
 (
-	log2	=   .693147180559945309e0;
-	ln10u1	=   .4342944819032518276511;
-	sqrto2	=   .707106781186547524e0;
-	p0	=  -.240139179559210510e2;
-	p1	=   .309572928215376501e2;
-	p2	=  -.963769093377840513e1;
-	p3	=   .421087371217979714e0;
-	q0	=  -.120069589779605255e2;
-	q1	=   .194809660700889731e2;
-	q2	=  -.891110902798312337e1;
+	ln10u1	= .4342944819032518276511;
 )
 
-export func Log(arg float64) float64 {
-	if arg <= 0 {
-		return sys.NaN();
-	}
-
-	x, exp := sys.frexp(arg);
-	for x < 0.5 {
-		x = x*2;
-		exp = exp-1;
-	}
-	if x < sqrto2 {
-		x = x*2;
-		exp = exp-1;
-	}
-
-	z := (x-1) / (x+1);
-	zsq := z*z;
-
-	temp := ((p3*zsq + p2)*zsq + p1)*zsq + p0;
-	temp = temp/(((zsq + q2)*zsq + q1)*zsq + q0);
-	temp = temp*z + float64(exp)*log2;
-	return temp;
-}
-
 export func Log10(arg float64) float64 {
 	if arg <= 0 {
 		return sys.NaN();
 	}
 	return Log(arg) * ln10u1;
 }
+
+