Constants in Problems

Provides constants in a PG problem.

Complete Code

PG problem file

Explanation

DOCUMENT();
loadMacros('PGstandard.pl', 'PGML.pl', 'PGcourse.pl');

Preamble

These standard macros need to be loaded.

Context()->constants->add(k => 0.023431412);

Context()->flags->set(formatStudentAnswer => 'parsed');

$ans = Compute('k');

Setup

Add the constant k with value 0.023431412 to the context. Choose a value for k that is not easy to guess, because if the value were guessed it would lead to unexpected results. For example, if a value of 1 were chosen, and a student entered 1 for the answer in this problem, then it would be counted as correct which is not desired.

Note that in this case constants->add is used, so that the constant k is added to existing constants in the context. If constants->are were used instead, then all existing constants would be removed from the context and k would be added as the only constant in the context. This is similar to the use of variables->add and variables->are when defining variables in a problem.

One other tweak that might be desired is to set a context flag so that student answers are not reduced to numerical values. This is done by setting formatStudentAnswer => 'parsed' as shown.

BEGIN_PGML
Let [`f(x) = x - k`] where [`k`] is a constant. Then [`f(x) = 0`] when
[`x =`] [___]{$ans}.
END_PGML

Statement

This is the problem statement in PGML.

BEGIN_PGML_SOLUTION
Solution explanation goes here.
END_PGML_SOLUTION

ENDDOCUMENT();

Solution

A solution should be provided here.