Two Kinds of Generalized Progressive Iterative Approximations
两类推广的渐近迭代逼近

In the field of computer aided design, the progressive iterative approximation (PIA) property of curves (surfaces) has wide applications in the interpolation and fitting problems, some previous works mainly discussed this PIA property in the case of normalized totally positive (NTP) basis. For general non-NTP basis, we point out that this good property also can be satisfied with some proper parameters, and many corresponding examples are given. Thus, the scope of applications of PIA can be widened. Furthermore, we discuss the convergence properties of weighted PIA with different weights, so that iterative approximation curves have different convergence rates near each data point.