dbsi0e.f
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