# dbesk0.f

          DOUBLE PRECISION FUNCTION DBESK0 (X)
    C***BEGIN PROLOGUE  DBESK0
    C***PURPOSE  Compute the modified (hyperbolic) Bessel function of the
    C            third kind of order zero.
    C***LIBRARY   SLATEC (FNLIB)
    C***CATEGORY  C10B1
    C***TYPE      DOUBLE PRECISION (BESK0-S, DBESK0-D)
    C***KEYWORDS  FNLIB, HYPERBOLIC BESSEL FUNCTION,
    C             MODIFIED BESSEL FUNCTION, ORDER ZERO, SPECIAL FUNCTIONS,
    C             THIRD KIND
    C***AUTHOR  Fullerton, W., (LANL)
    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
    C***REFERENCES  (NONE)
    C***ROUTINES CALLED  D1MACH, DBESI0, DBSK0E, DCSEVL, INITDS, XERMSG
    C***REVISION HISTORY  (YYMMDD)
    C   770701  DATE WRITTEN
    C   890531  Changed all specific intrinsics to generic.  (WRB)
    C   890531  REVISION DATE from Version 3.2
    C   891214  Prologue converted to Version 4.0 format.  (BAB)
    C   900315  CALLs to XERROR changed to CALLs to XERMSG.  (THJ)
    C***END PROLOGUE  DBESK0