sinc = function sinc(x) {

        // The value of sinc(0) is defined as 1
        if (x === 0)
            return 1;

        // Otherwise, normlized sinc(x) is sin(PI * x) / (PI * x)
        var piX = Math.PI * x;
        return Math.sin(piX) / piX;

    }
The normalized sinc function. The normalized sinc function is defined as
1 for x=0 and sin(PI * x) / (PI * x) for all other values of x.

See: https://en.wikipedia.org/wiki/Sinc_function

@private
@param {Number} x
    The point at which the normalized sinc function should be computed.

@returns {Number}
    The value of the normalized sinc function at x.