The BESSELI function Returns the modified Bessel function, In(x), which is equivalent to the Bessel function evaluated for purely imaginary arguments.




Argument Description
x The value at which the function is to be evaluated
n A positive integer, representing the order of the function. If the supplied value of n is a decimal, this is truncated to an integer by Excel

The chart on the right show Modified Bessel functions of 1st kind, Iα(x), for α = 0, 1, 2, 3

If you want to calculate the value of the order 1 modified Bessel function at x = 1.5, this can be done using the BESSELI function, as follows:


  A B C
1 Formula Result Notes
2 =BESSELI(1.5,1) 0.981666428 Modified Bessel function at 1.5 with an order of 1

Common Function Error(s)

Problem What went wrong
#VALUE! Occurs if any of the supplied arguments are non-numeric
#NUM! Occurs if the supplied value of n is < 0
#NAME? Occurs when Analysis ToolPak add-in is not enabled