Return to Formula_Response_Sampling.tex CVS log

Up to [LON-CAPA] / loncom / html / adm / help / tex

Annotation of loncom/html/adm/help/tex/Formula_Response_Sampling.tex, revision 1.2

1.2     ! bowersj2    1: \label{Formula_Response_Sampling}
1.1       bowersj2    2: 
                      3: As you may know, it is extremely difficult to determine whether a given expression
                      4: is exactly equal to another expression in general. For example, is $\sin 2x=2\sin x\cos x$?
                      5: Symbolically proving it one way or another is impossible in general. Therefore,
                      6: LON-CAPA uses a sampling system. If your answer and the student's answer
                      7: agree at the sampling points within your given tolerance factor, the student's
                      8: answer will be accepted, otherwise it will be rejected.
                      9: 
                     10: To specify where to sample the formulas for determining whether the student's
                     11: answer is correct, you need to put a sampling specification in the \textbf{Sample
                     12: Points}\index{Sample Points} field. The sampling specifications takes the
                     13: following format:
                     14: 
                     15: \begin{enumerate}
                     16: \item A comma separated list of the variables you wish to interpret,
                     17: \item followed by {}``@'' (not in quotes),
                     18: \item followed by any number of the following two things, separated by semi-colons:
                     19: 
                     20: \begin{enumerate}
                     21: \item a comma separated list of as many numbers as there are variables, which specifies
                     22: one sampling point, OR
                     23: \item a comma separated list of as many numbers as there are variables, followed
                     24: by a colon, followed by another list of as many numbers as there are variables,
                     25: followed by a \#, followed by an integer.
                     26: \end{enumerate}
                     27: \end{enumerate}
                     28: The first form specifies one point to sample. The second form specifies a
                     29: range for each variable, and the system will take as many random samples
                     30: from that range as the number after the \#.
                     31: 
                     32: For $2x^{2}+4$, with one variable {}``x'', one could specify
                     33: 
                     34: \begin{itemize}
                     35: \item {}``x@2'', which will sample the answers only at 2. (This is generally
                     36: a bad idea, as the student could get lucky and match at that point)
                     37: \item {}``x@1:5\#4'' will takes 4 samples from somewhere between 1 and 5.
                     38: \item {}``x@1:5\#4;10'' will takes 4 samples from somewhere between 1 and 5,
                     39: and also sample at 10.
                     40: \end{itemize}
                     41: For $2x^{2}+3y^{3}$, which has two variables, one could specify
                     42: 
                     43: \begin{itemize}
                     44: \item {}``x,y@4,5:10,12\#4;0,0'', which take four samples from the box determined
                     45: by the points (4, 5) and (10, 12), and also sample the point (0, 0).
                     46: \end{itemize}