--- loncom/homework/default_homework.lcpm	2014/06/24 17:02:33	1.165
+++ loncom/homework/default_homework.lcpm	2014/06/25 10:48:39	1.167
@@ -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 1.165 2014/06/24 17:02:33 raeburn Exp $
+# $Id: default_homework.lcpm,v 1.167 2014/06/25 10:48:39 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -1045,9 +1045,25 @@ sub format_significant_figures {
     my $numSig = $xint*10**($x10-$sig+$power);
     if ($numSig =~ /^(\d+)\.(\d+)/) {
         # insert trailing zero's if have decimal point
+        my @digarray = split('',$1.$2);
+        my $sigcount;
+        while (@digarray > 0) {
+            my $item = shift(@digarray);
+            if ($item) {
+                $sigcount = 1 + @digarray;
+                last;
+            }
+        }
+        if (($sigcount) && ($sig >= $sigcount)) {
+            $zeros = substr($zeros,0,($sig - $sigcount));
+        }
         $numSig =~ s/^(\d+)\.(\d+)(\e?(.*)?)$/$1\.$2$zeros$3/;
     } else {
-        if ($numSig =~ /0$/) {
+        if ($numSig =~ /^(\d+)e([\+\-]\d+)$/i) {
+            my $pre_exp = $1;
+            my $exponent = $2;
+            $numSig = $pre_exp.'.'.$zeros.'E'.$exponent;
+        } elsif ($numSig =~ /0$/) {
             # add decimal pt for number ending with 0 and length == # of sig figs
             if (length($numSig) == $sig) {
                 $numSig.='.';
@@ -1055,12 +1071,15 @@ sub format_significant_figures {
                 # exponential form for number ending with 0 and length > # of sig figs
                 my $fmtsig = $sig-1;
                 if ($fmtsig) {
-                    $numSig = sprintf('%.'.$fmtsig.'e',$numSig);
+                    $numSig = sprintf('%.'.$fmtsig.'E',$numSig);
                 }
+            } elsif (length($numSig) < $sig) {
+                $numSig.='.'.substr($zeros,0,($sig-length($numSig)));
+            }
+        } else {
+            if (length($numSig) < $sig) {
+                $numSig.='.'.substr($zeros,0,($sig-length($numSig)));
             }
-        }
-        if (length($numSig) < $sig) {
-            $numSig.='.'.substr($zeros,0,($sig-length($numSig)));
         }
     }
     # return number with sign