We will end this chapter with some special mathematical functions. The modified Bessel function of the first kind 0th order is represented in NumPy by i0(). The sinc function is represented in NumPy by a function with the same name, and there is also a two-dimensional version of this function. Sinc is a trigonometric function; for more details, see http://en.wikipedia.org/wiki/Sinc_function. The sinc() function has two definitions.

The NumPy sinc() function complies with the following definition: