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\label{Custom_Response_Problem_Creation} Custom Response is a way to have a problem graded based on an algorithm. The use of this response type is generally discouraged, since the responses will not be analyzable by the LON-CAPA statistics tools. For a single textfield, the student's answer will be in a variable \$submission. If the Custom Response has multiple textfields, the answers will be in an array reference, and can be accessed as \$\$submission[0], \$\$submission[1], etc. The student answer needs to be evaluated by Perl code inside the \texttt{$<$ answer$>$}-tag. Custom Response needs to include an algorithm that determines and returns a standard LON-CAPA response. The most common LON-CAPA responses are: \begin{itemize} \item EXACT\_ANS: return if solved exactly correctly \item APPROX\_ANS: return if solved approximately \item INCORRECT: return if not correct, uses up a try \item ASSIGNED\_SCORE: partial credit (also return the credit factor, \\ e.g. return(ASSIGNED\_SCORE,0.3);) \item SIG\_FAIL, NO\_UNIT, EXTRA\_ANSWER, MISSING\_ANSWER, BAD\_FORMULA, WANTED\_NUMERIC, WRONG\_FORMAT: return if not correct for different reasons, does not use up a try \end{itemize} The \texttt{answerdisplay} is shown instead of the student response in `show answer' mode after the answer date. The following example illustrates this: \begin{verbatim} <problem> <startouttext />Accept an answer of around 90 or -90<endouttext /> <customresponse answerdisplay="something near 90 or -90"> <answer type="loncapa/perl"> # This examples uses perl 'regular expressions' for string evaluation. # Consult a perl reference for help understanding the regular expressions. # We do not want a vector if ($submission=~/\,/) { return 'EXTRA_ANSWER'; } # Need a numerical answer here if ($submission!~/^[\d\.\-\e]+$/i) { return 'WANTED_NUMERIC'; } $difference=abs(90-abs($submission)); if ($difference==0) { return 'EXACT_ANS'; } if ($difference < 0.1) { return 'APPROX_ANS'; } return 'INCORRECT';</answer> <textline readonly="no" /> </customresponse> </problem> \end{verbatim} Full list of possible return codes: \begin{itemize} \item EXACT\_ANS: student is exactly correct \item APPROX\_ANS: student is approximately correct \item NO\_RESPONSE: student submitted no response \item MISSING\_ANSWER: student submitted some but not all parts of a response \item EXTRA\_ANSWER: student submitted a vector of values when a scalar was expected \item WANTED\_NUMERIC: expected a numeric answer and didn't get one \item SIG\_FAIL: incorrect number of Significant Figures \item UNIT\_FAIL: incorrect unit \item UNIT\_NOTNEEDED: submitted a unit when one shouldn't \item UNIT\_INVALID\_INSTRUCTOR: the unit provided by the author of the problem is unparsable \item UNIT\_INVALID\_STUDENT: the unit provided by the student is unparasable \item UNIT\_IRRECONCIBLE: the unit from the student and the instructor are of different types \item NO\_UNIT: needed a unit but none was submitted \item BAD\_FORMULA: syntax error in submitted formula \item WRONG\_FORMAT: student submission did not have the expected format \item INCORRECT: answer was wrong \item SUBMITTED: submission wasn't graded \item DRAFT: submission only stored \item MISORDERED\_RANK: student submitted a poorly order rank response \item ERROR: unable to get a grade \item ASSIGNED\_SCORE: partial credit; the customresponse needs to return the award followed by the partial credit factor \item TOO\_LONG: answer submission was deemed too long \item INVALID\_FILETYPE: student tried to upload a file that was of an extension that was not specifically allowed \item EXCESS\_FILESIZE: student uploaded file(s) with a combined size that exceeded the amount allowed \item COMMA\_FAIL: answer requires the use of comma grouping and it wasn't provided or was incorrect \end{itemize}