 
      FUNCTION BESK0(X)
C***BEGIN PROLOGUE  BESK0
C***DATE WRITTEN   770401   (YYMMDD)
C***REVISION DATE  820801   (YYMMDD)
C***CATEGORY NO.  C10B1
C***KEYWORDS  BESSEL FUNCTION,HYBERBOLIC BESSEL FUNCTION,
C             MODIFIED BESSEL FUNCTION,ORDER ZERO,THIRD KIND
C***AUTHOR  FULLERTON, W., (LANL)
C***PURPOSE  Computes the hyperbolic Bessel function of the third kind
C            of order zero
C***DESCRIPTION
C
C BESK0(X) calculates the modified (hyperbolic) Bessel function
C of the third kind of order zero for real argument X .GT. 0.0.
C
C Series for BK0        on the interval  0.          to  4.00000D+00
C                                        with weighted error   3.57E-19
C                                         log weighted error  18.45
C                               significant figures required  17.99
C                                    decimal places required  18.97
C***REFERENCES  (NONE)
C***ROUTINES CALLED  BESI0,BESK0E,CSEVL,INITS,R1MACH,XERROR
C***END PROLOGUE  BESK0
 
 
