 
      DOUBLE PRECISION FUNCTION DERF(X)
C***BEGIN PROLOGUE  DERF
C***DATE WRITTEN   770701   (YYMMDD)
C***REVISION DATE  840425   (YYMMDD)
C***CATEGORY NO.  C8A,L5A1E
C***KEYWORDS  DOUBLE PRECISION,ERROR FUNCTION,SPECIAL FUNCTION
C***AUTHOR  FULLERTON, W., (LANL)
C***PURPOSE  Computes the d.p. error function, ERF, of X.
C***DESCRIPTION
C
C DERF(X) calculates the double precision error function for double
C precision argument X.
C
C Series for ERF        on the interval  0.          to  1.00000E+00
C                                        with weighted error   1.28E-32
C                                         log weighted error  31.89
C                               significant figures required  31.05
C                                    decimal places required  32.55
C***REFERENCES  (NONE)
C***ROUTINES CALLED  D1MACH,DCSEVL,DERFC,INITDS
C***END PROLOGUE  DERF
 
 
