IMSL_KELVIN_BER0

Syntax | Return Value | Arguments | Keywords | Discussion | Example | Version History

The IMSL_KELVIN_BER0 function evaluates the Kelvin function of the first kind, ber, of order zero.

Note
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Syntax

Result = IMSL_KELVIN_BER0(x [, DERIVATIVE=value] [, /DOUBLE])

Return Value

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

Arguments

x

Argument for which the function value is desired.

Keywords

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.

DOUBLE

If present and nonzero, double precision is used.

Discussion

The Kelvin function ber₀(x) is defined to be ¬J₀(xe³π^i/4). 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 IMSL_KELVIN_BER0 function is based on the work of Burgoyne (1963).

Example

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

PRINT, IMSL_KELVIN_BER0(0.4) 
     0.999600 
PRINT, IMSL_KELVIN_BER0(0.6, /DERIVATIVE) 
   -0.0134985 

Version History