5 files changed, 22 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog
index 588d2f6f..1ad8d631 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2014-03-04  Kaz Kylheku  <kaz@kylheku.com>
+
+	* arith.c (logten): New function.
+
+	* eval.c (eval_init): logten registered as intrinsic.
+
+	* lib.h (logten): Declared.
+
+	* txr.1: Documented.
+
 2014-03-03  Kaz Kylheku  <kaz@kylheku.com>
 
 	* parser.l: Allowing ^ to be a quote character, and adjusting definition
diff --git a/arith.c b/arith.c
index f227f217..1eb9c5fb 100644
--- a/arith.c
+++ b/arith.c
@@ -1439,6 +1439,11 @@ val loga(val num)
   return flo(log(c_flo(to_float(lit("log"), num))));
 }
 
+val logten(val num)
+{
+  return flo(log10(c_flo(to_float(lit("log"), num))));
+}
+
 val expo(val num)
 {
   return flo(exp(c_flo(to_float(lit("exp"), num))));
diff --git a/eval.c b/eval.c
index 7936da92..51339182 100644
--- a/eval.c
+++ b/eval.c
@@ -3241,6 +3241,7 @@ void eval_init(void)
   reg_fun(intern(lit("atan"), user_package), func_n1(atang));
   reg_fun(intern(lit("atan2"), user_package), func_n2(atang2));
   reg_fun(intern(lit("log"), user_package), func_n1(loga));
+  reg_fun(intern(lit("log10"), user_package), func_n1(logten));
   reg_fun(intern(lit("exp"), user_package), func_n1(expo));
   reg_fun(intern(lit("sqrt"), user_package), func_n1(sqroot));
   reg_fun(intern(lit("cum-norm-dist"), user_package), func_n1(cum_norm_dist));
diff --git a/lib.h b/lib.h
index cb9a9762..e62eec93 100644
--- a/lib.h
+++ b/lib.h
@@ -497,6 +497,7 @@ val acosi(val);
 val atang(val);
 val atang2(val, val);
 val loga(val);
+val logten(val num);
 val expo(val);
 val logand(val, val);
 val logior(val, val);
diff --git a/txr.1 b/txr.1
index 22f99f62..deff8d86 100644
--- a/txr.1
+++ b/txr.1
@@ -9778,13 +9778,14 @@ functions.  The <num> argument to asin and acos must be in the
 range -1.0 to 1.0. The atan2 function converts the rectilinear coordinates
 <x>  and <y> to an angle in polar coordinates in the range [0, 2pi).
 
-.SS Functions log, exp
+.SS Functions exp, log, log10
 
 .TP
 Syntax:
 
   (exp <number>)
   (log <number>)
+  (log10 <number>)
 
 .TP
 Description:
@@ -9795,6 +9796,9 @@ the specified exponent.
 The log function calculates the base e logarithm of its argument, which must
 be a positive value.
 
+The log10 function calculates the base 10 logarithm of its argument, which must
+be a positive value.
+
 Integer arguments are converted to floats.
 
 .SS Functions expt, sqrt, isqrt