## WeBWorK Problems

### reduced fractions as the coordinate of a point

by Richard Lynch -
Number of replies: 2
Hello All! So we've covered forcing reduced fractions in lists and in intervals. How about points? I think it will be something similar as done in the case of intervals and we'll have to do

Context()->parens->set(
'(' => {type => 'Point'},
);
Context()->{precedence}{Fraction} = 2.5;

or something to keep points in the fraction context. Also, this is going to be used for intercepts of a function, so there may be multiple points. So what happens if I want to put the points in a list and force reduced fractions? I have no idea how to program the custom checker in either case. Any help is very much appreciated! Thanks!!

### Re: reduced fractions as the coordinate of a point

by Davide Cervone -
The custom checker is actually exactly the same as the one from the list of intervals case. Here is an example:
    Context("Fraction-NoDecimals");
Context()->{precedence}{Fraction} = 2.5;
Context()->parens->set('(' => {type => "Point"} );
Context()->flags->set(reduceFractions=>0);

$List = List("(1,2/5),(3/4,2)"); Context()->texStrings; BEGIN_TEXT $$List$$ = \{$List->ans_rule(20) \}
END_TEXT
Context()->normalStrings;

ANS($List->cmp( checker => sub { my ($correct, $student,$ans, $nth,$value) = @_;
$student->context->setError("Your$nth $value contains an unreduced fraction","",undef,undef,$Value::CMP_WARNING)
if $student->{notReduced}; return 0 unless$correct == $student; my$reduced = 1;
foreach $x ($student->value) {
if (Value::classMatch($x,'Fraction') && !$x->isReduced) {
$reduced = 0; break; } }$student->{notReduced} = 1 unless $reduced ||$ans->{isPreview};
return \$reduced;
}
));