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ppform

The items breaks, coefs, l, and k, make up the ppform of , along with the dimension d of its coefficients; usually d equals 1. The basic interval of this form is the interval [breaks(1) .. breaks(l+1)]. It is the default interval over which a function in ppform is plotted by the plot command fnplt.

In these terms, the precise description of the piecewise-polynomial is

= polyval(coefs(j,:), - breaks(j))

(4-1)

for .

Here, polyval(a,x) is the MATLAB function; it returns the number

This defines only for in the half-open interval [breaks(1)..breaks(l+1)). For any other , is defined by

i.e., by extending the first, respectively last, polynomial piece. In this way, a function in ppform has possible jumps, in its value and/or its derivatives, only across the interior breaks, breaks(2:l). The end breaks, breaks([1,l+1]), mainly serve to define the basic interval of the ppform.

Introduction

Construction

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