On 2018-03-28, saad khalid <saad1...@gmail.com> wrote:
> So, in this case,
> it Should assume that 3/1 is referring to the integer 3, use is_prime on
> the integer, and then also give a warning stating that 3/1 was interpreted
> as the integer 3. Then, we should have a function like is_prime_in_ring,
> which functions the way is_prime functions right now, ie it takes into
> account what the parent was instead of making the common simplification.
> The warning I mentioned earlier could even tell the use that if they want a
> ring dependent result, then they should use is_prime_in_ring. Again, the
> vast majority of users are assuming 3/1 = 3, and paying attention to the
> parent is a case of special usage.
That makes sense to me.
Thus I now think, z.is_prime() should roughly work like this:
def is_prime(self):
P = self.parent()
if P in Fields():
try:
R = P.ring_of_integers()
except AttributeError:
R = P
if self not in R:
return False
if P is not R:
deprecation(<relevant ticket>, """
You are testing primality of {},
which was constructed as an element of {}.
We assume that you want a primality test in {}. If this
was not your intention, use .is_prime_in_ring(<ring>)""".format(self,P,R))
P = R
return self.is_prime_in_ring(P)
and
def is_prime_in_ring(self,R=None):
if R is None:
R = self.parent()
return <whether self is a prime in R>
Not so sure if "deprecation" is the right thing, as the plan is not to
eventually remove a functionality. But at least in that way the warning
would be printed only once, and after all it *is* deprecated to use
is_prime for primality test in a field (use is_prime_in_ring instead).
Best regards,
Simon
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