PointAnswers1

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This article has been retained as a historical document. It is not up-to-date and the formatting may be lacking. Use the information herein with caution.

This problem has been replaced with a newer version of this problem


Answer is a Point or a List of Points

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This PG code shows how to evaluate answers that are points or lists of points.


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PG problem file Explanation

Problem tagging data

Problem tagging:

DOCUMENT();

loadMacros(
  'PGstandard.pl',
  'MathObjects.pl',
  'contextLimitedPoint.pl',
  'PGML.pl',
  'PGcourse.pl'
);

TEXT(beginproblem());

Initialization: We only need to load contextLimitedPoint.pl if we want to prevent operations between points.

Context('LimitedPoint');

$f = Compute('x^2-1');

$xint = List( Point('(1,0)'), Point('(-1,0)') );
$yint = List( Point('(0,-1)') );

Setup: We could have used Context("Point"); instead, which would allow mathematical operations between points (such as adding points as if they were vectors). The x-intercepts are clearly a list of points. We used a list with only one element for the y-intercepts so that a student who mistakenly enters two points will be told their second point is incorrect. If we did not use a list for the y-intercepts, a student who enters two points would be given an error message instead.

BEGIN_PGML
Enter the [`x`]-intercept(s) and [`y`]-intercept(s)
of [` y = [$f] `].  Enter a point as [` (a,b) `],
including the parentheses.  If there is more
than one correct answer, enter a comma
separated list of points.

+ [`x`]-intercept(s): [_________________]{$xint}

+ [`y`]-intercept(s): [_________________]{$yint}

[@ helpLink('points') @]*
END_PGML

Main Text: Be sure to tell students the proper syntax for how to enter their answers.

BEGIN_PGML_SOLUTION
Solution explanation goes here.
END_PGML_SOLUTION
ENDDOCUMENT();

Solution:

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