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### IMSL_KELVIN_BER0

IMSL_KELVIN_BER0

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

The Kelvin function ber0(x) is defined to be ¬J0(xe3pi/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`

## 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 (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

 6.4 Introduced