--- loncom/homework/default_homework.lcpm	2017/01/04 19:54:47	1.172
+++ loncom/homework/default_homework.lcpm	2019/11/06 16:20:06	1.177
@@ -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 1.172 2017/01/04 19:54:47 damieng Exp $
+# $Id: default_homework.lcpm,v 1.177 2019/11/06 16:20:06 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -29,6 +29,7 @@
 
 #init some globals
 $hidden::RANDOMINIT=0;
+$hidden::RANDOMINITTRYPART='';
 $pi=atan2(1,1)*4;
 $rad2deg=180.0/$pi;
 $deg2rad=$pi/180.0;
@@ -309,10 +310,13 @@ sub caparesponse_check_list {
 	#for numerical problems split off the unit
         my $part1;
         my $part2;
+        my $match_algebra = qr{^(.*[^\s])\s+([^\s]+)$};
+        # FIXME: with the above regexp, algebra with spaces will not be evaluated correctly
+        my $match_numerical_units = qr{^([\d\.\,\s\$]*(?:(?:[xX\*]10[\^\*]*|[eE]*)[\+\-]*\d*)*(?:^|\S)\d+)([\$\s\w\^\*\/\(\)\+\-]*[^\d\.\s\,][\$\s\w\^\*\/\(\)\+\-]*)$};
         if ($allowalgebra) {
-           ($part1,$part2)=($responses->[0][-1]=~ /^(.*[^\s])\s+([^\s]+)$/); 
+           ($part1,$part2) = ($responses->[0][-1] =~ /$match_algebra/); 
         } else {
-           ($part1,$part2)=($responses->[0][-1]=~ /^([\d\.\,\s\$]*(?:(?:[xX\*]10[\^\*]*|[eE]*)[\+\-]*\d*)*(?:^|\S)\d+)([\$\s\w\^\*\/\(\)\+\-]*[^\d\.\s\,][\$\s\w\^\*\/\(\)\+\-]*)$/);
+           ($part1,$part2) = ($responses->[0][-1] =~ /$match_numerical_units/);
         }
         if (defined($part1) && defined($part2)) {
 	    $responses->[0][-1]=$part1;
@@ -327,6 +331,27 @@ sub caparesponse_check_list {
                     }
                 }
             }
+            if (scalar(@$responses) > 0 && defined $answerunit) {
+                # there are several response values, units should be the same for all
+                $part2 =~ s/^\s+|\s+$//g;
+                for (my $i=1; $i<scalar(@$responses); $i++) {
+                    my $element = $responses->[$i][-1];
+                    my ($part1i, $part2i);
+                    if ($allowalgebra) {
+                        ($part1i, $part2i) = ($element =~ /$match_algebra/); 
+                    } else {
+                        ($part1i, $part2i) = ($element =~ /$match_numerical_units/);
+                    }
+                    $part2i =~ s/^\s+|\s+$//g;
+                    if (!defined $part2i) {
+                        return 'NO_UNIT';
+                    } elsif ($part2i ne $part2) {
+                        return ('UNIT_FAIL', "$part2 $part2i");
+                    } else {
+                        $responses->[$i][-1] = $part1i;
+                    }
+                }
+            }
 	}
     }
     $unit=~s/\s//;
@@ -631,19 +656,35 @@ sub hinton {
 
 sub random {
     my ($start,$end,$step)=@_;
-    if ( ! $hidden::RANDOMINIT ) {
-	if ($external::randomseed == 0) { $external::randomseed=1; }
-	if ($external::randomseed =~/,/) {
-	    my ($num1,$num2)=split(/,/,$external::randomseed);
-	    &random_set_seed(1,abs($num1));
-	} elsif ($external::randomseed =~/:/) {
-	    my ($num1,$num2)=split(/:/,$external::randomseed);
-	    &random_set_seed(abs($num1),abs($num2));
-	} else {
-	    &random_set_seed(1,int(abs($external::randomseed)));
-	}
+    if (( ! $hidden::RANDOMINIT ) ||
+        (($external::randomizetrypart ne '') &&
+         ($hidden::RANDOMINITTRYPART ne $external::randomizetrypart))) {
+        if ($external::randomseed == 0) { $external::randomseed=1; }
+        if ($external::randomseed =~/,/) {
+            my ($num1,$num2) = map { abs($_); } split(/,/,$external::randomseed);
+            if ((!$num1) || ($num1 > 2147483398)) {
+                &random_set_seed_from_phrase($external::randomseed);
+            } else {
+                &random_set_seed(1,$num1);
+            }
+        } elsif ($external::randomseed =~/:/) {
+            my ($num1,$num2) = map { abs($_); } split(/:/,$external::randomseed);
+            if ((!$num1) || (!$num2) || ($num1 > 2147483562) || ($num2 > 2147483398)) {
+                &random_set_seed_from_phrase($external::randomseed);
+            } else {
+                &random_set_seed($num1,$num2);
+            }
+        } else {
+            my $num1 = int(abs($external::randomseed));
+            if ((!$num1) || ($num1 > 2147483398)) {
+                &random_set_seed_from_phrase($external::randomseed);
+            } else {
+                &random_set_seed(1,$num1);
+            }
+        }
 	&math_random_uniform();
 	$hidden::RANDOMINIT=1;
+        $hidden::RANDOMINITTRYPART=$external::randomizetrypart;
     }
     if (!defined($step)) { $step=1; }
     my $num=1+int(($end-$start)/$step);
@@ -952,6 +993,18 @@ sub chemparse {
     return &xmlparse($formula);
 }
 
+sub conv_eng_format {
+    my ($ans,$baseunit)=@_;
+    my ($value,$answer,$unit);
+    $baseunit =~ s{[^\w/\-\.]}{}g; 
+    eval {
+           $value = &number_format_pref($ans);
+    };
+    my ($answer,$prefix) = ($value=~ /^(.+)(\w)$/);
+    my $unit = $prefix.$baseunit;
+    return($answer,$unit);
+} 
+
 sub prettyprint {
     my ($value,$fmt,$target)=@_;
     my $result;