[sage-devel] is_zero proof survey

1. Can you come up with a Sage parent (other than SR) where element.is_zero() is sometimes undecidable? 2. Same question where it is decidable but the current implementation is incomplete? Regards, -- You received this message because you are subscribed to the Google Groups "sage-devel" group.

[sage-devel] .is_zero() method for symbolic expression involving derivative

Hi, If a symbolic expression contains symbolic derivative then checking whether it is zero, raises error: -- sage: x.diff(x,2).is_zero() True sage: f(x).diff(x).is_zero() NotImplementedError: derivative -- This fails because new symbolics tries to convert it to maxima expression f

[sage-devel] is_zero()

Hi, I have some problems with the way is_zero() is implemented (or maybe it is the documentation...) Is this behavior really desirable? sage: k = var('k') sage: pol = 1/(k-1) - 1/k -1/k/(k-1) sage: pol -1/((k - 1)*k) - (1/k) + 1/(k - 1) sage: pol.partial_fraction() 0 sage: pol.is_zero() False sag

[sage-devel] is_zero

Hi there, many classes in SAGE implement and test for is_zero. I think these methods should be replaced with __nonzero__ methods, as this is the standard way of doing such a test in Python. For example, int doesn't have a is_zero(), such that one would have to test for a type (of a return val