KELVIN_BER0 Function (PV-WAVE Advantage)

Evaluates the Kelvin function of the first kind, ber, of order zero.

Usage

result = KELVIN_BER0(x)

Input Parameters

x—Argument for which the function value is desired.

Returned Value

result—The value of the Kelvin function of the first kind, ber, of order zero evaluated at x.

Input Keywords

Double—If present and nonzero, double precision is used.

Derivative—If present and nonzero, then the derivative of the Kelvin function of the first kind, ber, of order zero evaluated at x is computed.

Discussion

The Kelvin function ber0(x) is defined to be

. The Bessel function J0(x) is defined:

If the keyword Derivative is set, the function ber0'(x) is defined to be

If |x| > 119, NaN is returned.

The function KELVIN_BER0 is based on the work of Burgoyne (1963).

Example

In this example, ber0 (0.4) and ber0' (0.6) are evaluated.

PRINT, KELVIN_BER0(0.4)

; PV-WAVE prints: 0.999600

PRINT, KELVIN_BER0(0.6, /DERIVATIVE)

; PV-WAVE prints: -0.0134985

Version 2017.0