# dbesi0.f

          DOUBLE PRECISION FUNCTION DBESI0 (X)
    C***BEGIN PROLOGUE  DBESI0
    C***PURPOSE  Compute the hyperbolic Bessel function of the first kind
    C            of order zero.
    C***LIBRARY   SLATEC (FNLIB)
    C***CATEGORY  C10B1
    C***TYPE      DOUBLE PRECISION (BESI0-S, DBESI0-D)
    C***KEYWORDS  FIRST KIND, FNLIB, HYPERBOLIC BESSEL FUNCTION,
    C             MODIFIED BESSEL FUNCTION, ORDER ZERO, SPECIAL FUNCTIONS
    C***AUTHOR  Fullerton, W., (LANL)
    C***DESCRIPTION
    C
    C DBESI0(X) calculates the double precision modified (hyperbolic)
    C Bessel function of the first kind of order zero and double
    C precision argument X.
    C
    C Series for BI0        on the interval  0.          to  9.00000E+00
    C                                        with weighted error   9.51E-34
    C                                         log weighted error  33.02
    C                               significant figures required  33.31
    C                                    decimal places required  33.65
    C
    C***REFERENCES  (NONE)
    C***ROUTINES CALLED  D1MACH, DBSI0E, 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  DBESI0