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

This routine requires an IDL Advanced Math and Stats license. For more information, contact your sales or technical support representative.

The Kelvin function ber₀(x) is defined to be ¬J₀(xe³p^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

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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

Syntax

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

Return Value

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

Arguments

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X

Argument for which the function value is desired.

Keywords

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DERIVATIVE (optional)

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 (optional)

If present and nonzero, then double precision is used.

Version History

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6.4	Introduced

See Also

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IMSL_KELVIN_BEI0, IMSL_KELVIN_KEI0, IMSL_KELVIN_KER0