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

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