This function evaluates the exponentially scaled modified Bessel function of the first kind of order zero.

Function Return Value

BSI0E — Function value.   (Output)

Required Arguments

X — Argument for which the function value is desired.   (Input)

FORTRAN 90 Interface

Generic:                              BSI0E (X)

Specific:                             The specific interface names are S_BSI0E and D_BSI0E.

FORTRAN 77 Interface

Single:                                BSI0E (X)

Double:                              The double precision function name is DBSI0E.

Description

Function BSI0E computes e−|x| I0(x). For the definition of the Bessel function I0 (x), see BSI0.

Example

In this example, BSI0E(4.5) is computed and printed.

 

      USE BSI0E_INT

      USE UMACH_INT

 

      IMPLICIT   NONE

!                                 Declare variables

      INTEGER    NOUT

      REAL       VALUE, X

!                                 Compute

      X     = 4.5

      VALUE = BSI0E(X)

!                                 Print the results

      CALL UMACH (2, NOUT)

      WRITE (NOUT,99999) X, VALUE

99999 FORMAT (' BSI0E(', F6.3, ') = ', F6.3)

      END

Output

 

BSI0E( 4.500) =  0.194

http://www.vni.com/ PHONE: 713.784.3131 FAX:713.781.9260