 
      DOUBLE PRECISION FUNCTION DBESI1(X)
C***BEGIN PROLOGUE  DBESI1
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 ONE,SPECIAL FUNCTION
C***AUTHOR  FULLERTON, W., (LANL)
C***PURPOSE  Computes the d.p. modified (hyperbolic) Bessel function
C            of the first kind of order one.
C***DESCRIPTION
C
C DBESI1(X) calculates the double precision modified (hyperbolic)
C Bessel function of the first kind of order one and double precision
C argument X.
C
C Series for BI1        on the interval  0.          to  9.00000E+00
C                                        with weighted error   1.44E-32
C                                         log weighted error  31.84
C                               significant figures required  31.45
C                                    decimal places required  32.46
C***REFERENCES  (NONE)
C***ROUTINES CALLED  D1MACH,DBSI1E,DCSEVL,INITDS,XERROR
C***END PROLOGUE  DBESI1
 
 
