Sinc function

This article is about a particular entire function: a holomorphic function defined on the whole of $\mathbb {C}$
View a complete list of entire functions

Definition

The sinc function is defined in the following equivalent ways:

• It is given by the power series:

Failed to parse (unknown function "\sinc"): {\displaystyle \sinc z := \sum_{n=0}^\infty (-1)^n \frac{z^{2n}}{(2n + 1)!}}

• It is defined as:

Failed to parse (unknown function "\sinc"): {\displaystyle \sinc z := \frac{\sin z}{z}, \ z \ne 0, qquad \sinc 0 = 1}

• It is the difference quotient of the sine function, relative to the origin.

Related functions

• Its antiderivative is the sine integral, denoted $Si$