BER1
This function evaluates the Kelvin function of the first kind, ber, of order one.
Function Return Value
BER1 — Function value. (Output)
Required Arguments
X — Argument for which the function value is desired. (Input)
FORTRAN 90 Interface
Generic: BER1 (X)
Specific: The specific interface names are S_BER1 and D_BER1.
FORTRAN 77 Interface
Single: BER1 (X)
Double: The double precision name is DBER1.
Description
The Kelvin function ber
1(
x) is defined to be
ℜJ1(
xe3πi∕4). The Bessel function
J1(
x) is defined in
BSJ1. Function
BER1 is based on the work of Burgoyne (1963).
If ∣x∣ > 119, then NaN (not a number) is returned.
Example
In this example, ber1(0.4) is computed and printed.
USE BER1_INT
USE UMACH_INT
IMPLICIT NONE
! Declare variables
INTEGER NOUT
REAL VALUE, X
! Compute
X = 0.4
VALUE = BER1(X)
! Print the results
CALL UMACH (2, NOUT)
WRITE (NOUT,99999) X, VALUE
99999 FORMAT (' BER1(', F6.3, ') = ', F6.3)
END
Output
BER1( 0.400) = -0.144
