In digital signal processing and information theory, the normalized sinc function is commonly defined for x ≠ 0 by
The normalized sinc (blue) and unnormalized sinc function (red) shown on the same scale.
operatorname{sinc}(x) = frac{sin(pi x)}{pi x}~.
In either case, the value at x = 0 is defined to be the limiting value sinc(0) = 1.