PointAnswers1

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.

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: