scipy.special.
perm#
- scipy.special.perm(N, k, exact=False)[source]#
- Permutations of N things taken k at a time, i.e., k-permutations of N. - It’s also known as “partial permutations”. - Parameters:
- Nint, ndarray
- Number of things. 
- kint, ndarray
- Number of elements taken. 
- exactbool, optional
- If - True, calculate the answer exactly using long integer arithmetic (N and k must be scalar integers). If- False, a floating point approximation is calculated (more rapidly) using- poch. Default is- False.
 
- Returns:
- valint, ndarray
- The number of k-permutations of N. 
 
 - Notes - Array arguments accepted only for exact=False case. 
- If k > N, N < 0, or k < 0, then a 0 is returned. 
 - Examples - >>> import numpy as np >>> from scipy.special import perm >>> k = np.array([3, 4]) >>> n = np.array([10, 10]) >>> perm(n, k) array([ 720., 5040.]) >>> perm(10, 3, exact=True) 720