# besk1.f

          FUNCTION BESK1 (X)
    C***BEGIN PROLOGUE  BESK1
    C***PURPOSE  Compute the modified (hyperbolic) Bessel function of the
    C            third kind of order one.
    C***LIBRARY   SLATEC (FNLIB)
    C***CATEGORY  C10B1
    C***TYPE      SINGLE PRECISION (BESK1-S, DBESK1-D)
    C***KEYWORDS  FNLIB, HYPERBOLIC BESSEL FUNCTION,
    C             MODIFIED BESSEL FUNCTION, ORDER ONE, SPECIAL FUNCTIONS,
    C             THIRD KIND
    C***AUTHOR  Fullerton, W., (LANL)
    C***DESCRIPTION
    C
    C BESK1(X) computes the modified (hyperbolic) Bessel function of third
    C kind of order one for real argument X, where X .GT. 0.
    C
    C Series for BK1        on the interval  0.          to  4.00000D+00
    C                                        with weighted error   7.02E-18
    C                                         log weighted error  17.15
    C                               significant figures required  16.73
    C                                    decimal places required  17.67
    C
    C***REFERENCES  (NONE)
    C***ROUTINES CALLED  BESI1, BESK1E, 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  BESK1