--- loncom/homework/lonmaxima.pm	2017/03/07 18:28:02	1.37
+++ loncom/homework/lonmaxima.pm	2017/06/12 00:22:35	1.38
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Interface routines to MAXIMA CAS
 #
-# $Id: lonmaxima.pm,v 1.37 2017/03/07 18:28:02 raeburn Exp $
+# $Id: lonmaxima.pm,v 1.38 2017/06/12 00:22:35 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -118,7 +118,7 @@ sub runscript {
 sub maxima_cas_formula_fix {
    my ($expression)=@_;
    $expression=&Apache::response::implicit_multiplication($expression);
-   $expression=~s/([^\w\%])pi/$1\%pi/gs;
+   $expression=~s/(^|[^\w\%])pi(\W|$)/$1\%pi$2/gs;
    return $expression;
 }