[New-bugs-announce] [issue37128] Add math.perm()

[Serhiy Storchaka]

New submission from Serhiy Storchaka <storchaka+cpython at gmail.com>:

The function which returns the number of ways to choose k items from n items without repetition and without order was added in issue35431. This functions is always goes in pair with other function, which returns the number of ways to choose k items from n items without repetition and with order. These functions are always learned together in curses of combinatorics. Often C(n,k) is determined via P(n,k) (and both are determined via factorial).

    P(n, k) = n! / (n-k)!
    C(n, k) = P(n, k) / k!

The proposed PR adds meth.perm(). It shares most of the code with math.comb().

----------
components: Library (Lib)
messages: 344226
nosy: lemburg, mark.dickinson, serhiy.storchaka, stutzbach
priority: normal
severity: normal
status: open
title: Add math.perm()
type: enhancement
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue37128>
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