The modified Bessel function of the first kind of *z* in Math. Defined by

A solution of the differential equation

\[ \frac{d^2 f}{dz^2} + \frac{1}{z} \frac{df}{dz} - \left[ 1 + \frac{n^2}{z^2} \right] f = 0 \]The second linearly independent solution of this equation for integer order is besselK.

Real part on the real axis:

Imaginary part on the real axis:

Real part on the imaginary axis:

Imaginary part on the imaginary axis:

Real part on the complex plane:

Imaginary part on the complex plane:

Absolute value on the complex plane:

Related functions: besselK

Function category: Bessel functions