In this paper we propose, a collocation method to solve unsteady gas equation which is a nonlinear ordinary differential equation on semiinfnite interval. This approach is based on generalized Laguerre polynomials and rational Chebyshev functions. This method reduces the solution of this problem to the solution of a system of algebraic equations. We also present the comparison of this work with...

We introduce a method for constructing an element-by-element sparse approximate inverse (SAI) preconditioner designed to be effective in a massively-parallel spectral element modeling environment involving nonsymmetric systems. This new preconditioning approach is based on a spectral optimization of a low-resolution preconditioned system matrix (PSM). We show that the local preconditioning matr...

Interval LLL SIMPLEX HS Amoroso Lower # CP [-1, 1] 1/1.5314 1/1.5334 1/1.4772 1/1.4520 1/1.5417 8 [-1/2, 1/2] 1/2.3559 1/2.3619 1/2.1822 1/1.4520 1/2.3768 9 [-1/3, 1/3] 1/3.2522 1/3.2617 1/3.0000 1/1.3887 1/3.2842 7 [-2/3, 2/3] 1/1.8820 1/1.8883 1/1.7237 1/1.3887 1/1.9845 5 [-1/4, 1/4] 1/4.1921 1/4.2025 1/4.0000 1/1.1097 1/4.2260 6 [-3/4, 3/4] 1/1.7897 1/1.7935 1/1.7237 1/1.1097 1/1.9653 3 [-1/...

We study the problem of reconstructing a sparse polynomial in a basis of Chebyshev polynomials (Chebyshev basis in short) from given samples on a Chebyshev grid of [−1, 1]. A polynomial is called M -sparse in a Chebyshev basis, if it can be represented by a linear combination of M Chebyshev polynomials. For a polynomial with known and unknown Chebyshev sparsity, respectively, we present efficie...

We show that any compact, connected set in the plane can be approximated by the critical points of a polynomial with only two critical values. Date: April 2011. 1991 Mathematics Subject Classification. Primary: 30C62 Secondary:

Finite-dimensional representations of Onsager’s algebra are characterized by the zeros of truncation polynomials. The ZN -chiral Potts quantum chain hamiltonians (of which the Ising chain hamiltonian is the N = 2 case) are the main known interesting representations of Onsager’s algebra and the corresponding polynomials have been found by Baxter and Albertini, McCoy and Perk in 1987-89 consideri...

In this paper we review some group theoretic techniques applied to discretizations of PDEs. Inspired by the recent years active research in Lie groupand exponential time integrators for differential equations, we will in the first part of the article present algorithms for computing matrix exponentials based on Fourier transforms on finite groups. As an example, we consider spherically symmetri...

The Markoff equation is x+y+z = 3xyz, and all of the positive integer solutions of this equation occur on one tree generated from (1, 1, 1), which is called the Markoff tree. In this paper, we consider trees of solutions to equations of the form x + y + z = xyz + A. We say a tree of solutions satisfies the unicity condition if the maximum element of an ordered triple in the tree uniquely determ...

We begin with a compact figure that can be folded into smaller replicas of itself, such as the interval or equilateral triangle. Such figures are in one-to-one correspondence with affine Weyl groups. For each such figure in n-dimensional Euclidean space, we construct a sequence of polynomials P/c: Rn —► Rn so that the mapping P^ is conjugate to stretching the figure by a factor A; and folding i...

The main objective of this paper is to use the generalized proportional Hadamard fractional integral operator establish some new inequalities for extended Chebyshev functionals. In addition, we investigate positive continuous functions by employing a operator. findings study are theoretical but have potential help solve additional practical problems in mathematical physics, statistics, and appr...