Cesàro means of Jacobi expansions on the parabolic biangle

Wolfgang zu Castell, Frank Filbir, Yuan Xu

We study Cesàro $(C,\delta )$ means for two-variable Jacobi polynomials on the parabolic biangle $B=\{(x_1,x_2)\in {\mathbb{R}}^2:0\le x_1^2\le x_2\le 1\}$. Using the product formula de…