.BG
.VE $Header: /usr3/s/current/s/.help/RCS/gamma,v 1.2 83/12/30 19:28:38 rab Exp $
.FN gamma
.FN lgamma
.TL
gamma lgamma: Gamma Function (and its Natural Logarithm)
.CS
gamma(x)
lgamma(x)
.PP
.AG x
vector structure.  Missing values (NAs) are allowed.
.RT
gamma or natural log of gamma function evaluated for each value in
`x'.  For positive integral values, `gamma(x)' is `(x\-1)!'.  For
negative integral values, `gamma(x)' is undefined.  Function
`lgamma' allows only positive arguments.  NAs are returned
when evaluation would cause numerical problems.
.PP
Note that `gamma(x)' increases very rapidly with `x'. Use `lgamma' wherever
possible to avoid overflow.
.EX
gamma(6)   # same as 5 factorial
.KW basic*
.KW math
.KW factorial
.WR
