
Accession Number : ADA141606
Title : A Geometric Proof of Total Positivity for Spline Interpolation.
Descriptive Note : Technical summary rept.,
Corporate Author : WISCONSIN UNIVMADISON MATHEMATICS RESEARCH CENTER
Personal Author(s) : Boor,C de ; DeVore,R
PDF Url : ADA141606
Report Date : Apr 1984
Pagination or Media Count : 14
Abstract : The total positivity of the spline collocation matrix is the basis of several important results in univariate spline theory. This makes it desirable to provide as simple as possible a proof of this total positivity. The proofs available in the literature don't qualify since these all rely on certain determinant identities which are not exactly intuitive. The authors give a proof that uses nothing more than Cramer's rule (hard to avoid since total positivity is a statement about determinants) and the geometrically obvious fact that a Bspline can always be written as a positive combination of Bsplines on a finer knot sequence. The geometric intuition appealed to here stems from the area of ComputerAided Design in which a spline is constructed and manipulated through its Bpolygon, a broken line whose vertices correspond to the Bspline coefficients. If a knot is added (to provide greater potential flexibility), the new Bpolygon is obtained by interpolation to the old. This had led Lane and Riesenfeld to a proof of the variation diminishing property of the spline collocation matrix and is shown here to provide a proof of the total positivity as well.
Descriptors : *Splines(Geometry), *Interpolation, Matrices(Mathematics), Coefficients, Polygons, Variations, Computer aided design
Subject Categories : Theoretical Mathematics
Distribution Statement : APPROVED FOR PUBLIC RELEASE