This Excel tutorial explains how to use an Engineering function in Excel. Excel BESSELI function returns the modified Bessel functions I_{n}(x).

Syntax of the BESSELI function is BESSELI(x,n). So this function has two arguments. Both of them are mandatory. x is the value at which to evaluate the function. n represents the order of the function. And n should be positive. Function will return an error if n is less than 0.

And this is how you can use the function in the Excel.

In the above example I have passed the arguments by cell addresses. However you can pass the arguments like this as well

**=BESSELI(-5,1)**

This table shows the I_{n}(x) for x values from -5 to 5. Order of the function is 1.

And here is the graph for above table.

Then I changed the order of the function to 2 and calculated the I_{n}(x).

This is the graph for order 2.