BERP0

This function evaluates the derivative of the Kelvin function of the first kind, ber, of order zero.

Function Return Value

BERP0 — Function value. (Output)

Required Arguments

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

FORTRAN 90 Interface

Generic: BERP0 (X)

Specific: The specific interface names are S_BERP0 and D_BERP0.

FORTRAN 77 Interface

Single: BERP0 (X)

Double: The double precision name is DBERP0.

Description

The function berʹ0(x) is defined to be

 

where ber0(x) is a Kelvin function, see BER0. Function BERP0 is based on the work of Burgoyne (1963).

If ∣x∣ > 119, then NaN (not a number) is returned.

Example

In this example, berʹ0(0.6) is computed and printed.

 

USE BERP0_INT

USE UMACH_INT

 

IMPLICIT NONE

! Declare variables

INTEGER NOUT

REAL VALUE, X

! Compute

X = 0.6

VALUE = BERP0(X)

! Print the results

CALL UMACH (2, NOUT)

WRITE (NOUT,99999) X, VALUE

99999 FORMAT (' BERP0(', F6.3, ') = ', F6.3)

END

Output

 

BERP0( 0.600) = -0.013