I cannot get the absolute value function to graph. I get a warning message:

### Warning messages

`syntax error in answer:`

`(`**|**x|)

Illegal character at position 2 at line 454 of [PG]/macros/PGgraphmacros.pl`syntax error in answer:`

`(`**|**x|)

Illegal character at position 2 at line 458 of [PG]/macros/PGgraphmacros.pl

`Here is the code:-------------------------------------------------------------------`

`DOCUMENT(); # This should be the first executable line in the problem.`

`loadMacros(`

"PGstandard.pl",

"MathObjects.pl",

"contextInequalities.pl",

"parserUtils.pl"

);

`TEXT(beginproblem);`

`######################################`

# Setup

`#----Define the functions`

$f = Formula("abs(x)");

`$a = random(-4,-2,1);`

$g = Formula("$a");

`#---Define the graph`

($xm,$xM) = (-6,6); #min and max for x

($ym,$yM) = (-6,6); #min and max for y

$size = [300,300];

$tex_size = 600;

`@slice = NchooseK(3,3);`

@colors = ("blue", "red", "green");

@sc = @colors[@slice]; #scrambled colors

`@Goptions = (`

$xm,$ym,$xM,$yM,

axes => [0,0],

grid => [$xM-$xm,$yM-$ym],

size => $size

);

@imageoptions = (size=>$size,tex_size=>$tex_size);

`$xdomain = "x in <$xm,$xM>";`

$f_options = "using color:$sc[0] and weight:3";

$g_options = "using color:$sc[1] and weight:3";

`$graph = init_graph_no_labels(@Goptions);`

plot_functions($graph,

"$f for $xdomain $f_options",

"$g for $xdomain $g_options");

$labelf = new Label(-3,5, "f(x) = $f->string", 'black','center');

$labelg = new Label(3,$a, "y = $a",'black','center');

$graph->lb($labelf,$labelg);

`$Image = Image($graph,@imageoptions);`

`######################################`

# Main text

`BEGIN_TEXT`

$Image

$BR $BR

The graph of \( f(x) = \{$f->TeX\} \) is given above with the line \( y = $a \).

For what values of \(x\) is the following true?

$PAR

\( |x| = $a \)

`$BR`

Answer: \{ans_rule(20) \}

END_TEXT

`######################################`

# Answer

`Context("Inequalities");`

`$ans = Compute("NONE");`

ANS($ans->cmp);

$showPartialCorrectAnswers = 1;

`######################################`

`ENDDOCUMENT();`

-----------------------END CODE----------------------------------------------

`Thanks for your help -- rac`