[WWcvs] pg: Don't reduce -ax+b to b-ax in polynomial contexts.

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

Log Message:
-----------
Don't reduce -ax+b to b-ax in polynomial contexts.

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

Revision Data
-------------
Index: contextLimitedPolynomial.pl
===================================================================
RCS file: /webwork/cvs/system/pg/macros/contextLimitedPolynomial.pl,v
retrieving revision 1.20
retrieving revision 1.21
diff -Lmacros/contextLimitedPolynomial.pl -Lmacros/contextLimitedPolynomial.pl -u -r1.20 -r1.21
--- macros/contextLimitedPolynomial.pl
+++ macros/contextLimitedPolynomial.pl
@@ -417,9 +417,9 @@
     );
   }
   #
-  #  Don't convert -ax-b to -(ax+b), etc.
+  #  Don't convert -ax-b to -(ax+b), or -ax+b to b-ax, etc.
   #
-  $context->reduction->set("(-x)-y"=>0);
+  $context->reduction->set("(-x)-y"=>0,"(-x)+y"=>0);
 
   #
   #  A context where coefficients can't include operations