[aandrejevic] 67841: [FAST486] Due to some kind of mixup, I thought the series for log(x) was actually for log10(x). Fix Fast486FpuCalculateLogBase2 by dividing the result with log(2) and not log10...

Author: aandrejevic
Date: Thu May 21 17:27:47 2015
New Revision: 67841

URL: http://svn.reactos.org/svn/reactos?rev=67841&view=rev
Log:
[FAST486]
Due to some kind of mixup, I thought the series for log(x) was actually for log10(x).
Fix Fast486FpuCalculateLogBase2 by dividing the result with log(2) and not log10(2).

Modified:
    trunk/reactos/lib/fast486/fpu.c

Modified: trunk/reactos/lib/fast486/fpu.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/lib/fast486/fpu.c?rev=67841...
==============================================================================
--- trunk/reactos/lib/fast486/fpu.c	[iso-8859-1] (original)
+++ trunk/reactos/lib/fast486/fpu.c	[iso-8859-1] Thu May 21 17:27:47 2015
@@ -1085,8 +1085,8 @@

/*
  * Calculates using the identities:
- * log2(x) = log10(x) / log10(2)
- * log10(x)= sum { -1^(n+1) * x^n / n!, n >= 1 }
+ * log2(x) = ln(x) / ln(2)
+ * ln(x)= sum { -1^(n+1) * x^n / n!, n >= 1 }
  */
 static inline BOOLEAN FASTCALL
 Fast486FpuCalculateLogBase2(PFAST486_STATE State,
@@ -1144,7 +1144,7 @@
     /* Subtract one from the value */
     if (!Fast486FpuSubtract(State, &Value, &FpuOne, &Value)) return FALSE;

-    /* Calculate the base 10 logarithm */
+    /* Calculate the natural logarithm */
     SeriesElement = TempResult = Value;

for (i = 2; i < INVERSE_NUMBERS_COUNT / 2; i++)
@@ -1173,8 +1173,8 @@
         }
     }

-    /* Now convert the base 10 logarithm into a base 2 logarithm */
-    if (!Fast486FpuDivide(State, &TempResult, &FpuLgTwo, &TempResult)) return FALSE;
+    /* Now convert the natural logarithm into a base 2 logarithm */
+    if (!Fast486FpuDivide(State, &TempResult, &FpuLnTwo, &TempResult)) return FALSE;

/*
      * Add the exponent to the result