--- loncom/homework/default_homework.lcpm	2011/10/06 17:20:37	1.152.2.2
+++ loncom/homework/default_homework.lcpm	2013/01/21 06:16:50	1.163
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA 
 # used by lonxml::xmlparse() as input variable $safeinit to Apache::run::run()
 #
-# $Id: default_homework.lcpm,v 1.152.2.2 2011/10/06 17:20:37 raeburn Exp $
+# $Id: default_homework.lcpm,v 1.163 2013/01/21 06:16:50 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -253,8 +253,6 @@ sub caparesponse_check {
     elsif ($result =='15') { $result='UNIT_IRRECONCIBLE'; }
     else  {$result = "ERROR: Unknown Result:$result:$@:";}
 
-#    &LONCAPA_INTERNAL_DEBUG("RetError $reterror: Answer $answer: Response $response:  type-$type|$tol|$tol_type|$sig:$sig_lbound:$sig_ubound|$unit|");
-#    &LONCAPA_INTERNAL_DEBUG(" $answer $response $result ");
     return ($result,$reterror);
 }
 
@@ -265,7 +263,7 @@ sub caparesponse_check_list {
     my $type = $LONCAPA::CAPAresponse_args{'type'};
     my $answerunit=$LONCAPA::CAPAresponse_args{'unit'};
     &LONCAPA_INTERNAL_DEBUG("Got type :$type: answer unit :$answerunit:\n");
-    
+   
     my $preprocess=$LONCAPA::CAPAresponse_args{'preprocess'};
     $preprocess=~s/^\&//;
 
@@ -309,9 +307,10 @@ sub caparesponse_check_list {
     my ($allowalgebra)=($LONCAPA::CAPAresponse_args{'allowalgebra'}=~/^(yes|1|on)$/i);
     if ($type eq 'float' || $type eq '') {
 	#for numerical problems split off the unit
-        my ($part1,$part2);
+        my $part1;
+        my $part2;
         if ($allowalgebra) {
-           ($part1,$part2)=($responses->[0][-1]=~ /^(.*[^\s])\s+([^\s]+)$/);
+           ($part1,$part2)=($responses->[0][-1]=~ /^(.*[^\s])\s+([^\s]+)$/); 
         } else {
            ($part1,$part2)=($responses->[0][-1]=~ /^([\d\.\,\s\$]*(?:(?:[xX\*]10[\^\*]*|[eE]*)[\+\-]*\d*)*(?:^|\S)\d+)([\$\s\w\^\*\/\(\)\+\-]*[^\d\.\s\,][\$\s\w\^\*\/\(\)\+\-]*)$/);
         }
@@ -817,6 +816,7 @@ sub cos { CORE::cos(shift) }
 sub exp { CORE::exp(shift) }
 sub int { CORE::int(shift) }
 sub log { CORE::log(shift) }
+sub ln { CORE::log(shift) }
 sub atan2 { CORE::atan2($_[0],$_[1]) }
 sub sqrt { CORE::sqrt(shift) }
 
@@ -1033,6 +1033,17 @@ sub format_significant_figures {
     $number = abs($number);
     # needed to correct for a number greater than 1 (or
     my $power = ($number < 1) ? 0 : 1;
+    if ($power && $number =~ /^\d+$/) {
+        my $nonzeros = $number;
+        $nonzeros =~ s/0+$//;
+        if (length($number) - length($nonzeros) > 1) {
+            # convert to exponential form
+            my $n = $sig-1;
+            my $numSig = sprintf('%.' . $n . 'E', $number);
+            # return number with sign
+            return $sign.$numSig;
+        }
+    }
     # could round up. Take the integer part of log10.
     my $x10 = int(log($number)/log(10));
     # find number with values left of decimal pt = # of sign figs.
@@ -1183,7 +1194,7 @@ sub middlename {
     $middlename = '' if $middlename eq "";
     return $middlename;
 }
-                                                                                
+
 sub lastname {
     my $lastname = &EXT('environment.lastname');
     $lastname = '' if $lastname eq "";