# The Excel BESSELY Function

## Function Description

The Excel Bessely function returns the Bessel function, Yn(x), (also known as the Weber function or the Neumann function), for a specified order and value of x.

The syntax of the function is:

BESSELY( x, n )

where the function arguments are as follows:

 x - The value at which the function is to be evaluated. n - A positive integer, denoting the order of the Bessel function.(If the supplied value of n is a decimal, it is truncated to an integer by Excel).

## Bessely Function Example Order 1 Bessel Function Y1(x)

The above chart on the right shows the order 1 Bessel function, Y1(x).

If you want to calculate the value of this function at x = 0.05, this can be done using the Excel formula:

=BESSELY( 0.05, 1 )

which gives the result -12.78985516.

See the Microsoft Office website for further information on the Excel Bessely function.

## Bessely Function Errors

If you get an error from the Excel Bessely function this is likely to be one of the following:

Common Errors
 #NUM! - Occurs if either:The supplied value of x is ≤ 0orThe supplied value of n is < 0. #VALUE! - Occurs if any of the supplied arguments are non-numeric.