# besk0.f

          FUNCTION BESK0 (X)
    C***BEGIN PROLOGUE  BESK0
    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      SINGLE 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 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
    C***REFERENCES  (NONE)
    C***ROUTINES CALLED  BESI0, BESK0E, CSEVL, INITS, R1MACH, XERMSG
    C***REVISION HISTORY  (YYMMDD)
    C   770401  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   900326  Removed duplicate information from DESCRIPTION section.
    C           (WRB)
    C***END PROLOGUE  BESK0