mutwo.utilities.prime_factors¶
Prime number calculations.
The functions “factorise” and “factors” are copied from the pyprimes
library.
In mutwo the function pyprimes.primes() has been replaced by
primesieve.Iterator(), which improves speed by a factor of 10.
Functions:
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Yields tuples of (factor, count) where each factor is unique and usually prime, and count is an integer 1 or larger. |
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Test if number is prime or not. |
- factorise(integer) [list of factors][source]¶
- Parameters
n (int) – The number which shall be factorised.
- Returns
Returns a list of the (mostly) prime factors of integer n. For negative integers, -1 is included as a factor. If n is 0, 1 or -1, [n] is returned as the only factor. Otherwise all the factors will be prime.
- Return type
List[int]
Example:
>>> factorise(-693) [-1, 3, 3, 7, 11] >>> factorise(55614) [2, 3, 13, 23, 31]
- factors(integer) yield factors of integer lazily[source]¶
Yields tuples of (factor, count) where each factor is unique and usually prime, and count is an integer 1 or larger. The factors are prime, except under the following circumstances: if the argument n is negative, -1 is included as a factor; if n is 0 or 1, it is given as the only factor. For all other integer n, all of the factors returned are prime.
Example:
>>> list(factors(3*7*7*7*11)) [(3, 1), (7, 3), (11, 1)]
- Parameters
n (int) –