# scipy.special.comb¶

scipy.special.comb(N, k, exact=False, repetition=False)[source]

The number of combinations of N things taken k at a time.

This is often expressed as “N choose k”.

Parameters: N : int, ndarray Number of things. k : int, ndarray Number of elements taken. exact : bool, optional If exact is False, then floating point precision is used, otherwise exact long integer is computed. repetition : bool, optional If repetition is True, then the number of combinations with repetition is computed. val : int, ndarray The total number of combinations.

binom
Binomial coefficient ufunc

Notes

• Array arguments accepted only for exact=False case.
• If k > N, N < 0, or k < 0, then a 0 is returned.

Examples

>>> from scipy.special import comb
>>> k = np.array([3, 4])
>>> n = np.array([10, 10])
>>> comb(n, k, exact=False)
array([ 120.,  210.])
>>> comb(10, 3, exact=True)
120L
>>> comb(10, 3, exact=True, repetition=True)
220L


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