On Tue, 18 Dec 2012 09:16:05 +0100 Burcin Erocal <bur...@erocal.org> wrote:
> This was indeed intentional at the time. When writing the "new > symbolics" code based on pynac, William and I thought that this > behavior was the one that led to least confusion. > > Working with expression trees that involve relational objects can be > confusing: > > > f = x < y; > x<y > > -5*f; > -5*(x<y) > > sin(-5*f) + x^2; > x^2+sin(-5*(x<y)) > > If arithmetic with relational objects is left unevaluated as above, we > have no well established interface to work with these expressions. So > we chose the simple solution... > > > This decision led to a lot more confusion than expected and there was > an agreement to change it quite a while ago: > > http://trac.sagemath.org/sage_trac/ticket/7660 > > It should just be a matter of removing the block starting with > > if is_a_relational(left._gobj): > > in the _mul_, _add_, etc. methods of > sage.symbolic.expression.Expression. Patches are welcome. I posted a prototype patch on the ticket. Please try it out and comment on the ticket. http://trac.sagemath.org/sage_trac/ticket/7660#comment:12 Cheers, Burcin -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To post to this group, send email to sage-devel@googlegroups.com. To unsubscribe from this group, send email to sage-devel+unsubscr...@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel?hl=en.
