# Manuals/calci/BESSELI

**BESSELI(x,n)**

- is the value to evaluate the function
- is an integer which is the order of the Bessel function.
- BESSELI(), returns the modified Bessel Function In(x).

## Description

- This function gives the value of the modified Bessel function.
- Bessel functions is also called Cylinder Functions because they appear in the solution to Laplace's equation in cylindrical coordinates.
- Bessel's Differential Equation is defined as:

where is the arbitrary complex number.

- But in most of the cases α is the non-negative real number.
- The solutions of this equation are called Bessel Functions of order .
- Bessel functions of the first kind, denoted as .
- The order modified Bessel function of the variable is:

, where :

- This function will give the result as error when:

1. or is non numeric 2. , because is the order of the function.

## ZOS

- The syntax is to calculate BESSELI IN ZOS is .
- is the value to evaluate the function
- is an integer which is the order of the Bessel function.

- For e.g.,BESSELI(0.25..0.7..0.1,42)

## Examples

- BESSELI(3,2) = 2.245212431 this is the derivative of .
- BESSELI(5,1) = 24.33564185
- BESSELI(6,0) = 67.23440724
- BESSELI(-2,1) = -1.59063685
- BESSELI(2,-1) = #N/A (ORDER OF FUNCTION < 0).

## Related Videos

## See Also

## References