# dbesj1.f

          DOUBLE PRECISION FUNCTION DBESJ1 (X)
    C***BEGIN PROLOGUE  DBESJ1
    C***PURPOSE  Compute the Bessel function of the first kind of order one.
    C***LIBRARY   SLATEC (FNLIB)
    C***CATEGORY  C10A1
    C***TYPE      DOUBLE PRECISION (BESJ1-S, DBESJ1-D)
    C***KEYWORDS  BESSEL FUNCTION, FIRST KIND, FNLIB, ORDER ONE,
    C             SPECIAL FUNCTIONS
    C***AUTHOR  Fullerton, W., (LANL)
    C***DESCRIPTION
    C
    C DBESJ1(X) calculates the double precision Bessel function of the
    C first kind of order one for double precision argument X.
    C
    C Series for BJ1        on the interval  0.          to  1.60000E+01
    C                                        with weighted error   1.16E-33
    C                                         log weighted error  32.93
    C                               significant figures required  32.36
    C                                    decimal places required  33.57
    C
    C***REFERENCES  (NONE)
    C***ROUTINES CALLED  D1MACH, D9B1MP, DCSEVL, INITDS, XERMSG
    C***REVISION HISTORY  (YYMMDD)
    C   780601  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   910401  Corrected error in code which caused values to have the
    C           wrong sign for arguments less than 4.0.  (WRB)
    C***END PROLOGUE  DBESJ1