[issue40446] pow(a, b, p) where b=int((p-1)/2) spits out gibbrish for big p

Change by Tim Peters : -- resolution: fixed -> not a bug ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue40446] pow(a, b, p) where b=int((p-1)/2) spits out gibbrish for big p

Ammar Askar added the comment: And just to add on, the reason this gives you the correct result in Python 2 is that `/` performs integer division whereas in Python 3 the `/` operator provides a float as a result. See https://docs.python.org/3/howto/pyporting.html#division for more details.

[issue40446] pow(a, b, p) where b=int((p-1)/2) spits out gibbrish for big p

Steven D'Aprano added the comment: Hi, The behaviour you are calling "gibbrish" is correct, as the expression `(p-1)/2` calculates a 64-bit floating point number, which may lose precision even for small values of p, but will definitely lose precision for large p. Calling `int()` on that

[issue40446] pow(a, b, p) where b=int((p-1)/2) spits out gibbrish for big p

Basic ICT Repairs added the comment: Hi, I was calculating Legendre coefficients, and quadratic residues and encountered what I believe to be a bug while using this code: for a in range (5): exp=int((p-1)/2) x=pow(a,exp,p) print(x) If p is an odd prime, then x can

[issue40446] pow(a, b, p) where b=int((p-1)/2) spits out gibbrish for big p

New submission from Basic ICT Repairs : Hi, I was calculating Legendre coefficients, and quadratic residues and encountered what I believe to be a bug while using this code: for a in range (5): exp=int((p-1)/2) x=pow(a,exp,p) print(x) If p is an odd prime, then x can