The following problem runs without error messages

but when I display the answers

it doesn't show the equations x = 1, x= -1, y = 0.

Rather, it shows "x-1, x+1, y" as if the = symbol and the 0 were being dropped.

Any ideas?

cs

DOCUMENT();

loadMacros(

"PGstandard.pl",

"PGML.pl",

"MathObjects.pl",

"PGcourse.pl",

"parserNumberWithUnits.pl",

"contextArbitraryString.pl",

"parserMultiAnswer.pl",

"parserImplicitEquation.pl",

"parserPopUp.pl",

"contextInequalities.pl",

"PGgraphmacros.pl",

);

TEXT(beginproblem());

$showPartialCorrectAnswers = 1;

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

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

Context()->variables->set(

x=>{limits=>[-10,10]},

y=>{limits=>[-10,10]}

);

$menu_e = PopUp(["select one", "even", "odd", "neither"], "even");

$menu_o = PopUp(["select one", "even", "odd", "neither"], "odd");

$menu_n = PopUp(["select one", "even", "odd", "neither"], "neither");

BEGIN_PGML

Answer the following questions regarding the function

[`\frac{1}{1 - x^2}`].

Is the function even, odd or neither?

[________________________]{$menu_e}

What are all the horizontal and vertical asymptotes of the function, if any?

[________________________]{List(ImplicitEquation("x=1"),

ImplicitEquation("x=-1"),

ImplicitEquation("y=0"))}

END_PGML

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

ENDDOCUMENT();