AKEI1
This function evaluates the Kelvin function of the second kind, kei, of order one.
Function Return Value
AKEI1 — Function value. (Output)
Required Arguments
X — Argument for which the function value is desired. (Input)
It must be nonnegative.
FORTRAN 90 Interface
Generic: AKEI1 (X)
Specific: The specific interface names are S_AKEI1 and D_AKEI1.
FORTRAN 77 Interface
Single: AKEI1 (X)
Double: The double precision name is DKEI1.
Description
The modified Kelvin function kei1(x) is defined to be . The Bessel function K1(x) is defined in BSK1. Function AKEI1 is based on the work of Burgoyne (1963).
If x < 0, then NaN (not a number) is returned. If x  119, then zero is returned.
Example
In this example, kei1(0.4) is computed and printed.
 
USE UMACH_INT
USE AKEI1_INT
 
IMPLICIT NONE
! Declare variables
INTEGER NOUT
REAL VALUE, X
! Compute
X = 0.4
VALUE = AKEI1(X)
! Print the results
CALL UMACH (2, NOUT)
WRITE (NOUT,99999) X, VALUE
99999 FORMAT (' AKEI1(', F6.3, ') = ', F6.3)
END
Output
 
AKEI1( 0.400) = -1.444