Lobatto and Radau positive quadrature formulas for linear combinations of Jacobi polynomials

Abstract

For a given $\theta\in (-1,1)$, we find out all parameters $\alpha,\beta\in \{0,1\}$ such that, there exists a linear combination of Jacobi polynomials $J_{n+1}^{(\alpha,\beta)}(x)-C J_{n}^{(\alpha,\beta)}(x)$ which generates a Lobatto (Radau) positive quadrature formula of degree of exactness \textcolor{red}{$2n+2$ ($2n+1$)} and contains the point $\theta$ as a node. These positive quadratures are very useful in studying problems in one-sided polynomial $L_1$ approximation.