scholarly journals Zero location and asymptotic behavior for extremal polynomials with non-diagonal Sobolev norms

2010 ◽  
Vol 162 (12) ◽  
pp. 2225-2242 ◽  
Author(s):  
Ana Portilla ◽  
Yamilet Quintana ◽  
José M. Rodríguez ◽  
Eva Tourís
2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Ana Portilla ◽  
Yamilet Quintana ◽  
José M. Rodríguez ◽  
Eva Tourís

Let ℙ be the space of polynomials with complex coefficients endowed with a nondiagonal Sobolev norm∥ · ∥W1,p(Vμ), where the matrixVand the measureμconstitute ap-admissible pair for1≤p≤∞. In this paper we establish the zero location and asymptotic behavior of extremal polynomials associated to∥ · ∥W1,p(Vμ), stating hypothesis on the matrixVrather than on the diagonal matrix appearing in its unitary factorization.


2009 ◽  
Vol 111 (2) ◽  
pp. 205-218 ◽  
Author(s):  
Ana Portilla ◽  
José M. Rodríguez ◽  
Eva Tourís

2020 ◽  
pp. 1950019 ◽  
Author(s):  
A. Díaz González ◽  
G. López Lagomasino ◽  
H. Pijeira Cabrera

We consider extremal polynomials with respect to a Sobolev-type [Formula: see text]-norm, with [Formula: see text] and measures supported on compact subsets of the real line. For a wide class of such extremal polynomials with respect to mutually singular measures (i.e. supported on disjoint subsets of the real line), it is proved that their critical points are simple and contained in the interior of the convex hull of the support of the measures involved and the asymptotic critical point distribution is studied. We also find the [Formula: see text]th root asymptotic behavior of the corresponding sequence of Sobolev extremal polynomials and their derivatives.


2004 ◽  
Vol 2004 (5) ◽  
pp. 371-378 ◽  
Author(s):  
Rabah Khaldi

We study the asymptotic behavior ofLp(σ)extremal polynomials with respect to a measure of the formσ=α+γ, whereαis a measure concentrated on a rectifiable Jordan curve in the complex plane andγis a discrete measure concentrated on an infinite number of mass points.


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