BESSELK

Returns the modified Bessel function, which is equivalent to the Bessel functions evaluated for purely imaginary arguments.

If this function is not available, and returns the #NAME? error, install and load the Analysis ToolPak add-in.

On the Tools menu, click Add-Ins.
In the Add-Ins available list, select the Analysis ToolPak box, and then click OK.
If necessary, follow the instructions in the setup program.

Syntax

BESSELK(x,n)

X is the value at which to evaluate the function.

N is the order of the function. If n is not an integer, it is truncated.

Remarks

If x is nonnumeric, BESSELK returns the #VALUE! error value.
If n is nonnumeric, BESSELK returns the #VALUE! error value.
If n < 0, BESSELK returns the #NUM! error value.
The n-th order modified Bessel function of the variable x is:

where Jn and Yn are the J and Y Bessel functions, respectively.

Example

The example may be easier to understand if you copy it to a blank worksheet.

Create a blank workbook or worksheet.
Select the example in the Help topic. Do not select the row or column headers.

Selecting an example from Help
Press CTRL+C.
In the worksheet, select cell A1, and press CTRL+V.
To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Tools menu, point to Formula Auditing, and then click Formula Auditing Mode.

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A	B
Formula	Description (Result)
=BESSELK(1.5, 1)	Modified Bessel function at 1.5 with an order of 1 (0.277388)