# BESSELI function: Description, Usage, Syntax, Examples and Explanation

## What is BESSELI function in Excel?

BESSELI function is one of Engineering functions in Microsoft Excel that returns the modified Bessel function, which is equivalent to the Bessel function evaluated for purely imaginary arguments.

## Syntax of BESSELI function

BESSELI(X, N)

The BESSELI function syntax has the following arguments:

**X:**The value at which to evaluate the function.**N:**The order of the Bessel function. If n is not an integer, it is truncated.

## BESSELI formula explanation

- 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 of BESSELI function

Steps to follow:

1. Open a new Excel worksheet.

2. Copy data in the following table below and paste it in cell A1

Note: For formulas to show results, select them, press F2 key on your keyboard and then press Enter.

You can adjust the column widths to see all the data, if need be.

Formula |
Description |
Result |

=BESSELI(1.5, 1) | Modified Bessel function at 1.5 with an order of 1. | 0.981666428 |