# Documentation/How Tos/Calc: BESSELI function

From Apache OpenOffice Wiki

## BESSELI

Calculates the modified Bessel function of the first kind.

### Syntax:

**BESSELI(x; n)**

- returns the modified Bessel function of the first kind, of order
, evaluated at**n**.**x**

- The modified Bessel function of the first kind
, where*I*(_{n}*x*) =*i*(^{-n}J_{n}*ix*)is the * Bessel function of the first kind.*J*_{n}

### Example:

**BESSELI(1; 1)**

- returns
.**0.565159103992**

### Issues:

- This function currently appears in the AddIn category of the Function Wizard.