College of Idaho RationalExpEvaluator error

[lahvak]

The problem Library/CollegeOfIdaho/setAlgebra_06_01_MultDivRationalExpressions/61IntAlg_22_MultDivRatExp.pg causes the following error what the correct answer is entered:

PG question processing error messages

PG warning messages

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The evaluated answer is not an answer hash : ||.

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Warning messages

    Use of uninitialized value $new_rh_ans_evaluation_result in concatenation (.) or string at /opt/webwork/pg/lib/WeBWorK/PG/Translator.pm line 1337

As far as I can tell, entering an incorrect answer does not trigger this.

See also http://webwork.maa.org/moodle/mod/forum/discuss.php?d=4009 and http://webwork.maa.org/moodle/mod/forum/discuss.php?d=421.

[lahvak]

The problem seems to be more serious, my students now report frequent errors with three problems in my "rational expressions" set. All the problems seem to be from the CollegeOfIdaho collection, and they all use the RationalExpEvaluator from CofIdaho_macros.pl. They all give an error similar to the one above.

[jwj61]

This macro file has problems. It first screens if the student entered the right function, so badly wrong answers will be marked wrong and be ok. I just made a change to the macro file which fixes the one problem mentioned above, but there may be other issues.