Documentation/Calc Functions/BESSELI/en

Function name:
BESSELI

Category:
Add-in

Summary:
Calculates the value of a modified Bessel function of the first kind, usually referred to as In(x). n is the order of the function and x is the value at which the function is to be calculated.

Syntax:
BESSELI(X; N)

Returns:
Returns a real number which is the value of the modified Bessel function of the first kind, with a specified order, for a given value of x.

Arguments:
X is a real number, or a reference to a cell containing that number, which is the value at which the modified Bessel function of the first kind is to be calculated.

N is a non-negative integer, or a reference to a cell containing that number, which is the order of the modified Bessel function of the first kind.


 * If either X or N is non-numeric, then BESSELI reports a #VALUE! error.
 * If N is a non-integer value, then BESSELI truncates it to an integer.
 * If N is negative, then BESSELI reports an invalid argument error (Err:502).

Details specific to BESSELI function
The following figure shows a plot of the modified Bessel functions of the first kind for orders 0, 1, 2, and 3. Modified Bessel functions of the first kind are finite at the origin, x = 0. They exhibit odd or even parity depending on the order of the function, so that In(-x) = In(x) for even orders and In(-x) = -In(x) for odd orders.

ODF 1.2 indicates that the first argument to the BESSELI function should be an integer. However, this is considered an unnecessary limitation and Calc’s implementation caters for real values of X.

Related LibreOffice functions:
BESSELJ

BESSELK

BESSELY

ODF standard:
Section 6.16.12, part 2

Equivalent Excel functions:
BESSELI