Figure 13 shows the D^prime(r) functions for crystalline NAGP with x = 0 as obtained from the GEM data by the application of either a (a) Lorch or (b) step modification function with k_{max} = 39.1 A^{-1} and from (c) the XRD data by the application of a step modification function with k_{max} = 24.99 A^{-1}.