The first column in Table 1 lists functions that generate the reference surfaces.
P is taken as (5+x+3y) for each function listed in the first column of Table 1. If
the function is 100/P, then the reference surface is 100/(5+x+3y). The coordinate
system is –1 .. 1 in both the x- and y-directions. The second in column lists sums
of squares of deviations of the bilinear equation from the reference surfaces. The
third and fourth columns list the analogous sums as obtained by the four-point
quadratic equations (A) and (B). See section 2. The fifth column lists sums of
squares of deviations based on the cubic equation model for the four-point
rectangle described in section 3. Table 1 compares four models for ABDC.