From e8f7057f5911f6d676d773913692914214fad2db Mon Sep 17 00:00:00 2001
From: Dave Reisner <d@falconindy.com>
Date: Tue, 4 May 2010 18:34:47 -0400
Subject: [PATCH] specify ln to log() for natural log evaluation

---
 posty.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/posty.c b/posty.c
index cecebc6..24efb6a 100644
--- a/posty.c
+++ b/posty.c
@@ -189,6 +189,8 @@ int parse_mfunc(char *mfunc) {
     res = atan(op1);
   else if (strcmp(mfunc, "sqrt") == 0)
     res = sqrt(op1);
+  else if (strcmp(mfunc, "ln") == 0)
+    res = log(op1);
 
   if (verbose == 1)
     printf("%s(%.*f) = %.*f\n", mfunc, precision, op1, precision, res);
@@ -204,7 +206,7 @@ int parse_expression(char *expr) {
 
   char *token;
   static const char *operators = "+/*-%^";
-  static const char *mfuncs = "|sqrt|sin|cos|tan|asin|acos|atan|";
+  static const char *mfuncs = "|ln|sqrt|sin|cos|tan|asin|acos|atan|";
   static const char *constants = "|e|pi|";
   double operand;
   char *ptr;