Bivariate Lagrange interpolation at the Padua points: the ideal theory approach

The aim of this work is to show how symbolic computation can be used to perform multivariate Lagrange, Hermite and Birkhoff interpolation and help us to build more realistic interpolating functions. After a theoretical introduction in which we analyze the complexity of the method we shall focus our attention on applications.

We obtain estimates of the $L_p$-error of the bivariate polynomial interpolation on the Lissajous-Chebyshev node points for wide classes of functions including non-smooth functions of bounded variation in the sense of Hardy-Krause. The results show that $L_p$-errors of polynomial interpolation on the Lissajous-Chebyshev nodes have almost the same behavior as the polynomial interpolation in the case of the tensor product Chebyshev grid.

As we all known, there is still a long way for us to solve arbitrary multivariate Lagrange interpolation in theory. Nevertheless, it is well accepted that theories about Lagrange interpolation on special point sets should cast important lights on the general solution. In this paper, we propose a new type of bivariate point sets, quasi-tower sets, whose geometry is more natural than some known point sets such as cartesian sets and tower sets. For bivariate Lagrange interpolati...

Various algebraic multigrid algorithms have been developed for solving problems in scientific and engineering computation over the past decades. They have been shown to be well-suited for solving discretized partial differential equations on unstructured girds in practice. One key ingredient of algebraic multigrid algorithms is a strategy for constructing an effective prolongation operator. Among many questions on constructing a prolongation, an important question is how to e...

We first give a method to get multidimensional Leja sequences by considering intertwining sequences from one-dimensional ones. An application is the existence of explicit Leja sequences for the closed unit polydisc. Next, we deal with some applications in bidimensional Lagrange interpolation with intertwining Leja sequences. These results also require an explicit formula for the associated fundamental Lagrange polynomials with uniform estimates.

In this article, we propose a bivariate polynomial interpolation problem for matrices (BVPIPM), for real matrices of the order $m\times n$. In the process of solving the proposed problem, we establish the existence of a class of $mn$-dimensional bivariate polynomial subspaces (BVPS) in which the BVPIPM always posses a unique solution. Two formulas are presented to construct the respective polynomial maps from the space of real matrices of the order $m\times n$ to two of the p...

In this paper, we show how any Pad\'e approximant $[p/q]_f$ of a formal power series $f$ can be written under two different barycentric rational forms. These form depend on $p+q+1$ parameters which can be almost arbitrarily chosen.

In some fields such as Mathematics Mechanization, automated reasoning and Trustworthy Computing etc., exact results are needed. Symbolic computations are used to obtain the exact results. Symbolic computations are of high complexity. In order to improve the situation, exactly interpolating methods are often proposed for the exact results and approximate interpolating methods for the approximate ones. In this paper, we study how to obtain exact interpolation polynomial with ra...

The paper considers a symbolic approach to Prony's method in several variables and its close connection to multivariate polynomial interpolation. Based on the concept of universal interpolation that can be seen as a weak generalization of univariate Chebychev systems, we can give estimates on the minimal number of evaluations needed to solve Prony's problem.

To generalize the concept of Pad\'e approximation for functions to more than one variable, several definitions have been introduced. All definitions have advantages and disadvantages. The advantages of these approaches has been discussed in many articles. One of the main disadvantages of these methods are low convergence rate and the loss of information in computing with low degrees. In this work we present a new definition of the multivariate Pad\'e approximation, treated th...