 
      DOUBLE PRECISION FUNCTION DBESI0(X)
C***BEGIN PROLOGUE  DBESI0
C***DATE WRITTEN   770701   (YYMMDD)
C***REVISION DATE  820801   (YYMMDD)
C***CATEGORY NO.  C10B1
C***KEYWORDS  BESSEL FUNCTION,DOUBLE PRECISION,FIRST KIND,
C             MODIFIED BESSEL FUNCTION,ORDER ZERO,SPECIAL FUNCTION
C***AUTHOR  FULLERTON, W., (LANL)
C***PURPOSE  Computes the d.p. hyperbolic Bessel function of the first
C            kind of order zero.
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***REFERENCES  (NONE)
C***ROUTINES CALLED  D1MACH,DBSI0E,DCSEVL,INITDS,XERROR
C***END PROLOGUE  DBESI0
 
 
