On 24/09/15 03:47, Ralf Stephan wrote:
ex.is_zero(simplify=False)
ex.is_zero(simplify=True)
This fits if ex is an equality. But what about: if x>0 ?
Two functions are necessary for inequalities because (x>0).__nonzero__
is called by (x>0)._cmp_ in case of eg. uniq(list of exes) and
here print or alphabetical order is called for, not proof.
So there is still a need for hold/truth() etc it seems.
I like the is_zero which is consistent with the rest of Sage (ie
sage.structure.element.Element). But note that the default
implementation there is
def is_zero(self):
return not self
def __nonzero__(self):
return self != self._parent.zero()
I think that if a relation is fed into such a test it should have break
earlier if it was not expected. Note that in a context related to your
initial problem, this works
sage: matrix([x==3])
[x == 3]
Should it?
I do not like hold since it is already used as a keyword everywhere in
symbolics
sage: cos(pi, hold=True)
cos(pi)
Vincent
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