nobu	2016-07-12 20:53:43 +0900 (Tue, 12 Jul 2016)

  New Revision: 55641

  https://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=55641

  Log:
    math.c: use common constants
    
    * math.c (math_log1, math_log10): use common math constants
      instead of math function calls.

  Modified files:
    trunk/math.c
Index: math.c
===================================================================
--- math.c	(revision 55640)
+++ math.c	(revision 55641)
@@ -10,6 +10,9 @@ https://github.com/ruby/ruby/blob/trunk/math.c#L10
 **********************************************************************/
 
 #include "internal.h"
+#ifdef _MSC_VER
+# define _USE_MATH_DEFINES 1
+#endif
 #include <float.h>
 #include <math.h>
 #include <errno.h>
@@ -408,6 +411,13 @@ math_exp(VALUE obj, VALUE x) https://github.com/ruby/ruby/blob/trunk/math.c#L411
 # define log10(x) ((x) < 0.0 ? nan("") : log10(x))
 #endif
 
+#ifndef M_LN2
+# define M_LN2 0.693147180559945309417232121458176568
+#endif
+#ifndef M_LN10
+# define M_LN10 2.30258509299404568401799145468436421
+#endif
+
 static double math_log1(VALUE x);
 
 /*
@@ -466,7 +476,7 @@ math_log1(VALUE x) https://github.com/ruby/ruby/blob/trunk/math.c#L476
     /* check for pole error */
     if (d == 0.0) return -INFINITY;
 
-    return log(d) + numbits * log(2); /* log(d * 2 ** numbits) */
+    return log(d) + numbits * M_LN2; /* log(d * 2 ** numbits) */
 }
 
 #ifndef log2
@@ -559,7 +569,7 @@ math_log10(VALUE obj, VALUE x) https://github.com/ruby/ruby/blob/trunk/math.c#L569
     /* check for pole error */
     if (d == 0.0) return DBL2NUM(-INFINITY);
 
-    return DBL2NUM(log10(d) + numbits * log10(2)); /* log10(d * 2 ** numbits) */
+    return DBL2NUM(log10(d) + numbits * M_LN2/M_LN10); /* log10(d * 2 ** numbits) */
 }
 
 /*

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