#### Previous topic

scipy.special.expi

#### Next topic

scipy.special.factorial2

# scipy.special.factorial

`scipy.special.``factorial`(n, exact=False)

  The factorial function, n! = special.gamma(n+1).

  If exact is 0, then floating point precision is used, otherwise exact long integer is computed.

  - Array argument accepted only for exact=False case.
  - If n<0, the return value is 0.

  Parameters: | n : int or array_like of ints Calculate `n!`. Arrays are only supported with exact set to False. If `n < 0`, the return value is 0. exact : bool, optional The result can be approximated rapidly using the gamma-formula above. If exact is set to True, calculate the answer exactly using integer arithmetic. Default is False.
  Returns: | nf : float or int Factorial of n, as an integer or a float depending on exact.

  Examples

      >>> from scipy.special import factorial
      >>> arr = np.array([3,4,5])
      >>> factorial(arr, exact=False)
      array([   6.,   24.,  120.])
      >>> factorial(5, exact=True)
      120L