BSK1E

FNLSpecFunc : Bessel Functions : BSK1E

BSK1E

Function Return Value

Required Arguments

FORTRAN 90 Interface

FORTRAN 77 Interface

This function evaluates the exponentially scaled modified Bessel function of the second kind of order one.

Function Return Value

BSK1E — Function value. (Output)

Required Arguments

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

FORTRAN 90 Interface

Generic: BSK1E (X)

Specific: The specific interface names are S_BSK1E and D_BSK1E.

FORTRAN 77 Interface

Single: BSK1E (X)

Double: The double precision function name is DBSK1E.

Description

Function BSK1E computes exK1(x). For the definition of the Bessel function K1(x), see BSK1. The answer BSK1E = exK1(x) ≈ 1/x overflows if x is too close to zero.

Example

In this example, BSK1E(0.5) is computed and printed.

USE BSK1E_INT

USE UMACH_INT

IMPLICIT NONE

! Declare variables

INTEGER NOUT

REAL VALUE, X

! Compute

X = 0.5

VALUE = BSK1E(X)

! Print the results

CALL UMACH (2, NOUT)

WRITE (NOUT,99999) X, VALUE

99999 FORMAT (' BSK1E(', F6.3, ') = ', F6.3)

END

Output

BSK1E( 0.500) = 2.731