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# scipy.special.comb

`scipy.special.``comb`(N, k, exact=False, repetition=False)

  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.
  Returns: | val : int, ndarray The total number of combinations.

  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