gdelaurentis / pyadic Goto Github PK

Sorry, not sure if this related to the update just pushed, or some other issue, but now there seems to be some problem with the integers? Both with as_tuple and even with normal arithmetic... could be my misunderstanding of the correct behavior though. This is with the most recent version just pushed.

The powers of p have the same tuple representation

>>> PAdic(1,2,4)
1 + O(2^4)
>>> PAdic(2,2,4)
1*2 + O(2^5)
>>> PAdic(4,2,4)
1*2^2 + O(2^6)
>>> PAdic(1,2,4).as_tuple
(1, 0, 0, 0)
>>> PAdic(2,2,4).as_tuple
(1, 0, 0, 0)
>>> PAdic(4,2,4).as_tuple
(1, 0, 0, 0)

Normal arithmetic seems broken

>>> PAdic(2,2,4) + PAdic(2,2,4) == PAdic(4,2,4)
False
>>> PAdic(2,2,4) + PAdic(2,2,4)
1*2^2 + O(2^5)
>>> PAdic(4,2,4)
1*2^2 + O(2^6)

Thank you for this package, it has been really helpful trying to build an intuition for p-adic numbers. In playing around I came across an odd behavior that think may be a bug. Specifically, when converting from a negative integer -x I seem to get a different PAdic than when I convert from the equivalent trivial fraction(-x,1).

PAdic(-2, 2, 4)
12 + 12^2 + 12^3 + O(2^4)
PAdic(Q(-2,1), 2, 4)
12 + 12^2 + 12^3 + O(2^5)
Q(-2,1) == -2
True

May the circumstance of prime 2 has something weird.

Second, the significant digits. Could them not be figured out by the method itself instead of being indicated by users?

Thanks.

PAdic(Q(1/5), 5, 20)*5 should just produce 1, but instead gives 1*5^3 + 2*5^5 + 2*5^6 + 4*5^7 + 2*5^8 + 2*5^9 + 2*5^11 + 1*5^12 + 4*5^13 + 4*5^17 + 4*5^18 + 3*5^20 + 3*5^21 + 3*5^22 + O(5^23)

I believe this to be because a proper representation of 1/5 in 5-adic numbers is ...0000.1 . This would be 1*5^-1 in your representation, but that is not what is outputted. The issue also exists for other bases.