c = sinc(m) returns an array c whose elements are the sinc of the elements of the input: m.

The sinc function (normalized) is defined as:

$$\text{sinc}(x) = \begin{cases} \frac{\sin(\pi x)}{\pi x} & \text{if } x \neq 0 \\ 1 & \text{if } x = 0 \end{cases}$$

The sinc function is the Fourier transform of the rectangular pulse function and appears frequently in signal processing and communications.