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1.1     ! raeburn     1: \label{Authoring_Daxe_Variables}
        !             2: 
        !             3: \textbf{Creating a Problem with Randomized Values}
        !             4: 
        !             5: Some randomization can easily be achieved with a radio button response, 
        !             6: by setting thei\texttt{randomize} attribute to 'yes', setting the
        !             7: \texttt{max} attribute to a maximum number of displayed foils, 
        !             8: and creating more foils than will be displayed.
        !             9: 
        !            10: With a numerical response, it is necessary to create variables with random values.  
        !            11: This can be done with a Perl script. Such a script is created by inserting a
        !            12: \texttt{script} element (in the \textit{Block} menu) and setting its
        !            13: \texttt{type} attribute to '\texttt{loncapa/perl}'.
        !            14: 
        !            15: Here is a little cookbook for randomizing values with a Perl script:
        !            16: \begin{itemize}
        !            17:   \item To set variable a to the value 1:
        !            18: 
        !            19: \texttt{\$a = 1;}
        !            20: 
        !            21:   \item To set variable a to the value 'text':
        !            22: 
        !            23: \texttt{\$a = 'text';}
        !            24: 
        !            25: Note that single quotes take the value literally, while double quotes replace variables by their values.
        !            26: 
        !            27:   \item To pick a random number between 1 and 5 (included), with a step of 0.5:
        !            28: 
        !            29: \texttt{\$a = random(1, 5, 0.5);}
        !            30: 
        !            31: (the step can be omitted to use a step of 1)
        !            32: 
        !            33:   \item To chose a value randomly in a list of text entries:
        !            34: 
        !            35: \begin{verbatim}
        !            36: @list = ('one', 'two', 'three');
        !            37: $n = random(1, scalar(@list));
        !            38: $a = choose($n, @list);\end{verbatim}
        !            39: 
        !            40:   \item Math operators:
        !            41: 
        !            42: \texttt{+, -, *, /, **, \%}
        !            43: 
        !            44:   \item Math functions:
        !            45: 
        !            46: \texttt{sin, cos, tan, asin, acos, atan, atan2, log, log10, exp, pow, sqrt, abs, sgn, erf, erfc, ceil, floor, min, max, factorial, sinh, cosh, tanh, asinh, acosh, atanh}
        !            47: 
        !            48:   \item Comments:
        !            49: 
        !            50: \texttt{\# This is a comment.}
        !            51: \end{itemize}
        !            52: 
        !            53: Once created in a script, variables can be used anywhere afterwards, still prefixed with
        !            54: \texttt{\$}. In particular, a numerical response answer can be set to a variable.