Return to Tolerance.tex CVS log

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

Annotation of loncom/html/adm/help/tex/Tolerance.tex, revision 1.1

1.1     ! bowersj2    1: A \textbf{tolerance\index{tolerance}} parameter determines how closely
        !             2: the system will require the student's answer to be in order to count it correct.
        !             3: 
        !             4: 
        !             5: For technical reasons, it is almost never a good idea to set this parameter
        !             6: to zero. Computers can only approximate computations involving real numbers. For instance,
        !             7: a computer's {[}decimal{]} answer to the simple problem $\frac{1}{3}$ is
        !             8: {}``0.33333333333333331''. It \emph{should} be an infinite series of 3's,
        !             9: and there certainly shouldn't be a {}``1'' in the answer, but no computer
        !            10: can represent an infinitely long, infinitely detailed real number. Therefore,
        !            11: for any problem where the answer is not a small integer, you \emph{need}
        !            12: to allow a tolerance factor, or the students will find it nearly impossible
        !            13: to exactly match the computers idea of the answer. You may find the
        !            14: default too large for some problems. 
        !            15: 
        !            16: There are
        !            17: two kinds of tolerance. For some answer $a$ and a tolerance $t$,
        !            18: 
        !            19: \begin{enumerate}
        !            20: \item an \textbf{Absolute} tolerance\index{absolute tolerance}\index{tolerance, absolute}
        !            21: will take anything in the range $a\pm t$. So if $a=10$ and $t=2$, then
        !            22: anything between 8 and 12 is acceptable.
        !            23:  Any number in the tolerance field \emph{without} a \textbf{\%} symbol is
        !            24: an absolute tolerance.
        !            25: \item a \textbf{Relative} tolerance\index{relative tolerance}\index{tolerance, relative}
        !            26: will take anything in the range $a\pm at$, where \emph{t} is interpreted
        !            27: as a percentage. Any number in the tolerance field \emph{followed by} a \textbf{\%}
        !            28: symbol is a relative tolerance. For example, $a=10$ and $t=10\%$ will accept
        !            29: anything between 9 and 11. 
        !            30: \end{enumerate}