arXiv subjects
Publications and source records attributed to Abdelhamid Rehouma.
Let $\{Q_{n}(x)\}$ be a system of integral Legendre polynomials of degree exactly n,and let $\{P_{n}(x)\}$ be polar polynomials primitives of integral Legendre polynomials. We derive some identities and relations and extremal problems and minimization involving of polar integral Legendre polynomials.
We use Gronwall's area formula to find the area of some differents regions as circles, ellipses and lemniscates.We use Laurent and Taylor series expansions of conformal mapping from the exterior of the unit disk to either of these regions to compute the area of them.We close this work with the discussion of orthogonal Tchebychev polynomials of second kind on the ellipse and interpolation.
Let $E$ be a Jordan rectifiable curve in the complex plane and let $G$ be the bounded component of $\mathbb{C}\backslash E$. Now let $n\in \mathbb{N}$, and let $m_{n,E}$ denote the extremal constants defined by \begin{equation*}m_{n,E}=\inf \left\{ \left\Vert \dfrac{D_{E,ρ}\left( z\right) }{D_{E,ρ}\left( 0\right) }-P_{n}\left( z\right) \right\Vert_{L^{p}\left(G,ρ\right) }:P_{n}\left( ξ\right) =1\right\}\end{equation*}where $ξ$ is a fixed complex number.where $ρ$ is a weight function, $D_{E,ρ}\left( \cdot \right)$ is the so called {Szegö} function, $z\in G$, $p\geq 2.$ The infimum is taken over all polynomials $P_{n}$ of degree $n$. The $L_{p}$ associated extremal polynomials $\left\{Q_{n}\right\}_{n=1,2....}$ satisfies \begin{equation*} m_{n,E}=\left\Vert \dfrac{D_{E,ρ}\left( z\right) }{D_{E,ρ}\left(0\right) }-Q_{n}\left( z\right) \right\Vert_{L^{p}\left( G,ρ\right) }.\end{equation*} We define the functions, if $p\in $ $\mathbb{N}$ \begin{equation*}J_{n}\left( z\right) =\int_{ξ_{G}}^{z}Q_{n}^{p}\left( t\right) dt;\;z\in G\end{equation*} which are of course well defined polynomials for any $n\in \mathbb{N}$. Following the same convention , we define the function \begin{equation*}Φ\left( z\right) =\int\limits_{ξ_{G}}^{z}\left( \dfrac{D_{E,ρ}\left( t\right) }{D_{E,ρ}\left( 0\right) }\right) ^{p}dt,\end{equation*} Our main target in this paper is to show that when $m_{n,E}\longrightarrow0, $ then \begin{equation*}J_{n}\left( z\right) \text{ }\longrightarrow Φ\left( z\right)\end{equation*} uniformly on compact subsets of $G.$
We derive some identities and relations and extremal problems and minimization and Fourier development involving of integral Legendre polynomials.
We derive a useful result about the zeros of the $k$-polar polynomials on the unit circle; in particular we obtain a ring shaped region containing all the zeros of these polynomials. Some examples are presented.