Category:Elliptic: Difference between revisions

This category contains all control problems which are governed by an elliptic partial differential equation.

A second order linear partial differential equation can be written as ${\displaystyle {\displaystyle \sum _{i,j=1}^n}{a}_{i,j}\frac{{\partial }^2}{\partial x_i\partial x_j}+\text{<mrow data-mjx-texclass="ORD">lower<mo stretchy="false">−</mo>orderterms</mrow>}=0}$. If ${\displaystyle A=(a_{i,j}{)}_{i,j}}$ is positive or negative definite, the partial differential equation is called elliptic. An example is the Poisson's equation: ${\displaystyle -\mathrm{\Delta }u=f}$, where ${\displaystyle \mathrm{\Delta }}$ denotes the Laplace operator, ${\displaystyle u}$ is the unknown, and the function ${\displaystyle f}$ given.