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

## What is BESSELK function in Excel?

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

## Syntax of BESSELK function

BESSELK(X, N)

The BESSELK function syntax has the following arguments:

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

## BESSELK formula explanation

- 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 of BESSELK 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 |

=BESSELK(1.5, 1) | Modified Bessel function at 1.5 with an order of 1. | 0.277387804 |