ψ ψ ( x ) = { 1 / 2 a for | x | ≤ ≤ a , 0 for | x | > a then its Fourier transform is the sinc function, φ φ ( p ) = a π π ℏ ℏ ⋅ ⋅ sinc ⁡ ⁡ ( a p ℏ ℏ ) which yields infinite momentum variance despite having a centralized shape. The entropic uncertainty, on the other hand, is finite. Suppose for simplicity that the spatial resolution is just a two-bin measurement, δx = a, and that the momentum resolution is δp = h / a.