Am 01.10.17 um 23:27 schrieb Daniel Bastos:
def make_sequence_non_recursive(N, x0 = 2, c = -1):
"What's wrong with this function? It's very slow."
last = x0
def sequence():
nonlocal last
next = last
last = last**2 + c
return next % N
return sequence
It crawls pretty soon. Please advise? Thank you.
You seem to do modular arithmetics with modulus N. You can take the
modulus after each single operation. This line:
last = last**2 + c
will quadratically grow the internal state of the generator. Instead,
you should write
last = (last**2 + c) % N
If I have understood what it does, then the result should be the same.
Furthermore, as Chris said, Python has built-in generators for this thing.
Christian
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