# The BESSELK function

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(known as Bessel's differential equation) for an arbitrary complex number a, the order of the Bessel function. Although a Y −α produce the same differential equation for real a, It is conventional to set different Bessel functions for these two values ​​in such a way that the Bessel functions are mostly smooth functions of a.

This is not intended to be a math lecture. I'll be out of my depth very quickly. Essentially, Excel has four modified Bessel functions, that specialists can use when needed. BESSELK returns the modified Bessel function, which is similar to Bessel functions evaluated for purely imaginary arguments.

The BESSELK The function uses the following syntax:

The BESSELK The function has the following arguments:

• X: required. This is the value at which to examine the function
• North: additionally required. This represents the order of the Bessel function. And North it is not a whole number, is truncated accordingly.

It should be noted at the same time that:

• And X it is not numeric, BESSELK return the #VALUE! error value
• And North it is not numeric, BESSELK return the #VALUE! error value
• And North <0, BESSELK return the #ON ONE! error value
• The Northth modified order Bessel function of variable X it is: