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# BESSELI function

This article describes the formula syntax and usage of the BESSELI function in Microsoft Excel.

## Description

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

## Syntax

BESSELI(X, N)

The BESSELI function syntax has the following arguments:

• X    Required. The value at which to evaluate the function.

• N    Required. The order of the Bessel function. If n is not an integer, it is truncated.

## Remarks

• If x is nonnumeric, BESSELI returns the #VALUE! error value.

• If n is nonnumeric, BESSELI returns the #VALUE! error value.

• If n < 0, BESSELI returns the #NUM! error value.

• The n-th order modified Bessel function of the variable x is:

## Example

Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.

Formula

Description

Result

=BESSELI(1.5, 1)

Modified Bessel function at 1.5 with an order of 1.

0.981666428