Several of my students had NO problems with the question below. One student on a Mac had the "Cannot generate enough points for comparison" error. Another student also on a Mac had the same error for a similar question.

Why only seems to affect Macs? How fix?

Thanks!

cs

DOCUMENT();

loadMacros(

"MathObjects.pl",

"PGstandard.pl",

"PGML.pl",

"PGcourse.pl",

"parserNumberWithUnits.pl",

"contextArbitraryString.pl",

"parserMultiAnswer.pl",

"parserPopUp.pl",

"contextInequalities.pl",

"PGgraphmacros.pl",

);

TEXT(beginproblem());

$showPartialCorrectAnswers = 1;

######################################################################

Context("Numeric") ; Context()->flags->set(tolerance => 0.01);

Context()->variables->add(t => "Real");

BEGIN_PGML

Find the derivative of [`\sqrt{9x^3 - 4}`].

[________________________]{"27*x^2/(2*sqrt(9*x^3 - 4))"}

END_PGML

######################################################################

ENDDOCUMENT();