 
      DOUBLE PRECISION FUNCTION DBESK0(X)
C***BEGIN PROLOGUE  DBESK0
C***DATE WRITTEN   770701   (YYMMDD)
C***REVISION DATE  820801   (YYMMDD)
C***CATEGORY NO.  C10B1
C***KEYWORDS  BESSEL FUNCTION,DOUBLE PRECISION,MODIFIED BESSEL FUNCTION,
C             ORDER ZERO,SPECIAL FUNCTION,THIRD KIND
C***AUTHOR  FULLERTON, W., (LANL)
C***PURPOSE  Computes  d.p. modified (hyperbolic) Bessel function of
C            the third kind of order zero.
C***DESCRIPTION
C
C DBESK0(X) calculates the double precision modified (hyperbolic)
C Bessel function of the third kind of order zero for double
C precision argument X.  The argument must be greater than zero
C but not so large that the result underflows.
C
C Series for BK0        on the interval  0.          to  4.00000E+00
C                                        with weighted error   3.08E-33
C                                         log weighted error  32.51
C                               significant figures required  32.05
C                                    decimal places required  33.11
C***REFERENCES  (NONE)
C***ROUTINES CALLED  D1MACH,DBESI0,DBSK0E,DCSEVL,INITDS,XERROR
C***END PROLOGUE  DBESK0
 
 
