Here is a list of all related documentation pages:

Book Reference Index
B-Spline Foundations
Curve Fitting Theory
Surface Fitting Theory
Polar and Spherical Domains
Univariate Curve Fitting with fitpack_curve
Periodic Curve Fitting
Parametric, Closed, and Constrained Curves
Convexity-Constrained Curve Fitting
Scattered Surface Fitting Tutorial
Grid and Parametric Surface Tutorial
Polar Domain Fitting Tutorial
Spherical Spline Fitting Tutorial