[WWcvs] pg: Fixed a problem that caused errors to occur when ImplicitPlane() was

[dpvc v. a. <we...@ma...>]

Log Message:
-----------
Fixed a problem that caused errors to occur when ImplicitPlane() was
called with a formula whose constant term is a negative number that is
produced by a computation.

Modified Files:
--------------
    pg/macros:
        parserImplicitPlane.pl

Revision Data
-------------
Index: parserImplicitPlane.pl
===================================================================
RCS file: /webwork/cvs/system/pg/macros/parserImplicitPlane.pl,v
retrieving revision 1.3
retrieving revision 1.4
diff -Lmacros/parserImplicitPlane.pl -Lmacros/parserImplicitPlane.pl -u -r1.3 -r1.4
--- macros/parserImplicitPlane.pl
+++ macros/parserImplicitPlane.pl
@@ -104,8 +104,8 @@
     #
     #  Find the coefficients of the formula
     #
-    my $f = Value::Formula->new($plane->{tree}{lop}) -
-	    Value::Formula->new($plane->{tree}{rop});
+    my $f = (Value::Formula->new($plane->{tree}{lop}) -
+	     Value::Formula->new($plane->{tree}{rop}))->reduce;
     my $F = $f->perlFunction(undef,[@{$vars}]);
     my @v = split('','0' x scalar(@{$vars}));
     $d = -&$F(@v); my @coeff = (@v);