(2.18) Though other orthonormalization strategies are possible, such as QR decomposition, using Equation (2.17 It is worthwhile to consider if the orthogonal basis parameters have a physical interpretation. Figure plots orthogonal basis functions and parameters to illustrate their properties. Panel A shows the shapes of the orthonormalized basis vectors stored in the rows of O B . As the number of pure exponential basis curves in B increases, the shapes of the orthogonalized basis curves in O B approach a limit for finely- basis curves. This limiting shape is already approximated very well using a relatively small numbers of basis curves. Figure Panel C shows that the importance of the orthonormal basis functions decreases rapidly, and the behavior is quite similar regardless of the number of basis functions used.