DOUBLE PRECISION FUNCTION DFAC(N)
C***BEGIN PROLOGUE  DFAC
C***DATE WRITTEN   770601   (YYMMDD)
C***REVISION DATE  820801   (YYMMDD)
C***CATEGORY NO.  C1
C***KEYWORDS  DOUBLE PRECISION,FACTORIAL,SPECIAL FUNCTION
C***AUTHOR  FULLERTON, W., (LANL)
C***PURPOSE  Computes the d.p. factorial of N.
C***DESCRIPTION
C
C DFAC(N) calculates the double precision factorial for integer
C argument N.
C***REFERENCES  (NONE)
C***ROUTINES CALLED  D9LGMC,DGAMLM,XERROR
C***END PROLOGUE  DFAC