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Usage:
Keywords:
special functions, integers
factorial(x) computes x! (x factorial), where x is a REAL scalar,
vector, matrix or array. The result is the same size and shape as
as x. If any element is MISSING, <= -1 or such that x! is too large
to be computed, the corresponding element of the result is MISSING.
Elements of x need not be integers. x! is computed as exp(lgamma(x+1)),
except that if x is an integer <= 20 the value should be exact.
See also binom() and lgamma().
Gary Oehlert
2003-01-15