Log Message:
-----------
Add error messages when student's answer is not linear in the constant
he or she has used.
Modified Files:
--------------
pg/macros:
parserFormulaUpToConstant.pl
Revision Data
-------------
Index: parserFormulaUpToConstant.pl
===================================================================
RCS file: /webwork/cvs/system/pg/macros/parserFormulaUpToConstant.pl,v
retrieving revision 1.3
retrieving revision 1.4
diff -Lmacros/parserFormulaUpToConstant.pl -Lmacros/parserFormulaUpToConstant.pl -u -r1.3 -r1.4
--- macros/parserFormulaUpToConstant.pl
+++ macros/parserFormulaUpToConstant.pl
@@ -71,6 +71,14 @@
#
# ANS($f->cmp(showHints => 0));
#
+ # One of the hints is about whether the student's answer is linear
+ # in the arbitrary constant. This test requires differentiating
+ # the student answer. Since there are times when that could be
+ # problematic, you can disable that test via the showLinearityHints
+ # flag. (Note: setting showHints to 0 also disables these hints.)
+ #
+ # ANS($f->cmp(showLinearityHints => 0));
+ #
######################################################################
=cut
@@ -157,10 +165,18 @@
return abs($context->variables->get("n0")->{value}) < $context->flag("zeroLevelTol");
}
+##################################################
+#
+# Here we override part of the answer comparison
+# routines in order to be able to generate
+# helpful error messages for students when
+# they leave off the + C.
+#
+
#
# Show hints by default
#
-sub cmp_defaults {((shift)->SUPER::cmp_defaults,showHints => 1)};
+sub cmp_defaults {((shift)->SUPER::cmp_defaults,showHints => 1, showLinearityHints => 1)};
#
# Add useful messages, if the author requested them
@@ -170,12 +186,16 @@
$self->SUPER::cmp_postprocess($ans);
return unless $ans->{score} == 0 && !$ans->{isPreview};
return if $ans->{ans_message} || !$self->getFlag("showHints");
- my $result = $ans->{correct_value} <=> $ans->{student_value}; # compare encodes the reason in the result
+ my $student = $ans->{student_value};
+ my $result = $ans->{correct_value} <=> $student; # compare encodes the reason in the result
$self->cmp_Error($ans,"Note: there is always more than one posibility") if $result == 2 || $result == 3;
$self->cmp_Error($ans,"Your answer is not the most general solution")
- if $result == 1 || ($result == 3 && $self->removeConstant == $ans->{student_value});
+ if $result == 1 || ($result == 3 && $self->removeConstant == $student);
+ $self->cmp_Error($ans,"Your formula should be linear in the constant '$student->{constant}'")
+ if $result == -1 && $self->getFlag("showLinearityHints") && !$student->D($student->{constant})->isConstant;
}
+##################################################
#
# Get the name of the constant
#
@@ -239,5 +259,4 @@
$self->SUPER::new($equation,$name,$ref);
}
-
1;
|
