"William Stein" <[EMAIL PROTECTED]> writes: > Sage Enhancement Proposal: Change comparisons that involve > elements of the symbolic ring to return True or False if both sides > of the symbolic comparison are constants and the comparison can > be definitely determined.
I'm not sure what symbolic equations are currently used for, but this kind of special casing can cause problems. If I'm building up an equation using inputs that I don't control, my code may have unexpected problems if what it thinks is a symbolic equation turns into a boolean. Maybe the heart of the matter is that we need a separate notation for symbolic equations vs. comparison. E.g. sage: 3 == pi False sage: 3 === pi 3 === pi sage: 1.2 == 1.3 False sage: 1.2 === 1.3 1.2 === 1.3 Note that this gives you the ability to have symbolic equations when the components happen to not be symbolic. (Does this even make sense given the current set-up?) I'm not sure what to do if the user requests a comparison that sage can't easily determine: sage: sqrt(3) + sqrt(8) == sqrt(5) + pi One idea would be to return a symbolic equation sqrt(3) + sqrt(8) === sqrt(5) + pi but probably the best is to raise an exception: if my code is expecting a boolean, then a symbolic equation may confuse it. So my SEP would be that == always returns a boolean or raises an exception, and === always returns a symbolic equation. The notation === is of course a topic for discussion. If === is chosen, it would have to use the pre-processor. Is there another operator that would make sense? Dan --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
