SLATEC Routines --- DBSI0E ---

*DECK DBSI0E
      DOUBLE PRECISION FUNCTION DBSI0E (X)
C***BEGIN PROLOGUE  DBSI0E
C***PURPOSE  Compute the exponentially scaled modified (hyperbolic)
C            Bessel function of the first kind of order zero.
C***LIBRARY   SLATEC (FNLIB)
C***CATEGORY  C10B1
C***TYPE      DOUBLE PRECISION (BESI0E-S, DBSI0E-D)
C***KEYWORDS  EXPONENTIALLY SCALED, FIRST KIND, FNLIB,
C             HYPERBOLIC BESSEL FUNCTION, MODIFIED BESSEL FUNCTION,
C             ORDER ZERO, SPECIAL FUNCTIONS
C***AUTHOR  Fullerton, W., (LANL)
C***DESCRIPTION
C
C DBSI0E(X) calculates the double precision exponentially scaled
C modified (hyperbolic) Bessel function of the first kind of order
C zero for double precision argument X.  The result is the Bessel
C function I0(X) multiplied by EXP(-ABS(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 Series for AI0        on the interval  1.25000E-01 to  3.33333E-01
C                                        with weighted error   2.74E-32
C                                         log weighted error  31.56
C                               significant figures required  30.15
C                                    decimal places required  32.39
C
C Series for AI02       on the interval  0.          to  1.25000E-01
C                                        with weighted error   1.97E-32
C                                         log weighted error  31.71
C                               significant figures required  30.15
C                                    decimal places required  32.63
C
C***REFERENCES  (NONE)
C***ROUTINES CALLED  D1MACH, DCSEVL, INITDS
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***END PROLOGUE  DBSI0E