Power-Surface: Power-Series LSq-Fitting & Saw-File 1.4

Power-Surface offers linear/ quadratic/ higher-power least-square curve/ surface fitting for the given column-wise numeric data for a function z = f(x) or z = f(x,y) of one or two independent variable(s), so that the fitted function is of the form z = a + b.x + c.x2 +... or z = a + b.x + c.y + d.x2 + e.xy + f.y2 +... respectively. To perform the fitting, the aforesaid algebraic power series function is assumed, and then the sum of the squares of deviations of z-values (for the given points) from the assumed function-value is minimized, thereby generating a set of linear simultaneous equations.

This set is then auto-solved by standard Gaussian-elimination method, giving the fitting parameters (coefficients) a, b, c etc. (users should refer to the tutorials). To avoid calculation errors, constant factors and decimal-points in the given (x,y,z) data are first shifted but finally re-corrected. The Saw-File subroutine allows vertical copying/pasting of numeric data columns from text files.