Cfrtjryk

I would like to create variables to hold strings like f(x)=3x+1 to be inputted into an exam questions.

I can create variables like funA, funB, … et cetera. The problem is how do I reference them using A, B, … et cetera.

documentclass[12pt]{exam}



% conditional statements

usepackage{xifthen}



newcommand{exam}{A}



newcommand{funA}{$s(t) = 12t^2 -7t + 16$}

newcommand{funB}{$s(t) = 16t^2 +3t + 10$}

newcommand{funC}{$s(t) = 12t^2 + t + 10.$}



begin{document}



begin{questions}



question % I would like funexam to return funA when exam = a. Sadly it doesn't 



The position of an object moving along a straight line is given by funexam. Find the average velocity of the object over the interval $[1,1+h]$ where $h>0$ is a real number.



question % this works but is a lot to write when accommodating 10 stored functions



ifthenelse{equal{exam}{A}}

    {

        newcommand{function}{$s(t) = 12t^2 -7t + 16.$}

    }

    {

        ifthenelse{equal{exam}{B}}

            {

                newcommand{function}{$s(t) = 16t^2 +3t + 10.$}

            }

            {

                newcommand{function}{$s(t) = 12t^2 + t + 10.$}

            }

    }



The position of an object moving along a straight line is given by function Find the average velocity of the object over the interval $[1,1+h]$ where $h>0$ is a real number.



end{questions}

end{document}

TeX allows you to reference control sequence names using a csname...endcsname pair. Any command inside this csname...endcsname pair will be expanded (i.e.: replaced by its meaning) until only unexpandable tokens are left, then TeX creates a control sequence out of the contents passed to csname...endcsname.

For instance, if you have newcommand{exam}{A}, then csname funAendcsname and csname funexamendcsname will both expand to funA. You can create a wrapper command to avoid writing csname...endcsname every single time:

documentclass[12pt]{exam}



newcommand{exam}{A}



newcommand{fun}[1]{csname fun#1endcsname}

% or:

% newcommand{fun}{csname funexamendcsname}, then use just fun instead of funexam

newcommand{funA}{$s(t) = 12t^2 -7t + 16$}

newcommand{funB}{$s(t) = 16t^2 +3t + 10$}

newcommand{funC}{$s(t) = 12t^2 + t + 10$}



begin{document}



begin{questions}



question



The position of an object moving along a straight line is given by funexam. Find the average velocity of the object over the interval $[1,1+h]$ where $h>0$ is a real number.



end{questions}

end{document}