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bpo-37178: Allow a one argument form of math.perm() (GH-13905)

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Raymond Hettinger 2019-06-08 08:58:11 -07:00 • committed by GitHub
parent 8cc605acdd
commit e119b3d136
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6 changed files with 34 additions and 9 deletions
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10
Modules/mathmodule.c
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@ -3002,7 +3002,7 @@ math_prod_impl(PyObject *module, PyObject *iterable, PyObject *start)
math.perm
n: object
k: object
k: object = None
/
Number of ways to choose k items from n items without repetition and with order.
@ -3010,18 +3010,24 @@ Number of ways to choose k items from n items without repetition and with order.
Evaluates to n! / (n - k)! when k <= n and evaluates
to zero when k > n.
If k is not specified or is None, then k defaults to n
and the function returns n!.
Raises TypeError if either of the arguments are not integers.
Raises ValueError if either of the arguments are negative.
[clinic start generated code]*/
static PyObject *
math_perm_impl(PyObject *module, PyObject *n, PyObject *k)
/*[clinic end generated code: output=e021a25469653e23 input=b2e7729d9a1949cf]*/
/*[clinic end generated code: output=e021a25469653e23 input=5311c5a00f359b53]*/
{
PyObject *result = NULL, *factor = NULL;
int overflow, cmp;
long long i, factors;
if (k == Py_None) {
return math_factorial(module, n);
}
n = PyNumber_Index(n);
if (n == NULL) {
return NULL;