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Interval

Consider the case that the answer to a problem is an interval or an union of disjoint intervals.

The optional TeX command \allowIntervalUnionsForInput[true] enables the option that the student's answer can be given by the union of multiple intervals.

Solution syntax

The solution is defined by a left and a right boundary , both seperated by a semicolon.

boundary symbol
open left ( or ]
closed left [
open right ) or [
closed right ]

e.g. \solution{(-1;1]}, \solution{]-1;1]} (same interval as the first one), \solution{(myVar;100[}

The correct solution as an union of multiple disjoint intervals can be given by separating them with a comma. E.g. \solution{(-infinity;2],[3;infinity)} Be aware that this is only possible if the optional command \allowIntervalUnionsForInput[true] is used.

Examples

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\begin{answer}
    \type{input.interval}
    \text{Write down the interval from 1 to 3:}
    \solution{[1;3]}
\end{answer}
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\begin{answer}
    \type{input.interval}
    \text{input.interval: $[1;4) = $}
    \allowIntervalUnionsForInput
    \solution{[1;4)}
\end{answer}

Capture

More Examples

Interval boundaries with multiple of π

If you want, that the solution and/or the answer boundaries can be written as multiple of π, use the command \allowForInput{pi}.

Example

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\begin{answer}
    \type{input.interval}
    \text{input.interval: $[\pi;4\cdot\pi) = $}
    \allowForInput{pi * / + - . ,}
    \solution{[pi;4*pi)}
\end{answer}

Interval boundaries with variables

If you want, that the solution and/or the answer boundaries contain variables and not just numbers, use the command \checkAsFunction.
It works the same way as it does for input type input.function:

\checkAsFunction[options]{<variable>}{<low>}{<high>}{<steps>}

will automatically be a valid input. The answer will be numerically compared with the solution based on the command's parameters.

Example

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\begin{answer}
    \type{input.interval}
    \text{input.interval: $[-k;2k) = $}
    \checkAsFunction[0.001]{k}{-1}{1}{10}
    \solution{[-k;2k)}
\end{answer}

In this example the answer will be compared numerically for 10 random values of k between -1 and 1. The difference beween answer and solution cannot be equal or bigger than 0.001.