Category:Hyperbolic: Difference between revisions

This category contains all control problems which are governed by a hyperbolic partial differential equation.

A second order linear partial differential equation can be written as ${\displaystyle {\displaystyle \sum _{i,j=1}^n}{a}_{ij}\frac{{\partial }^{2}u}{\partial x_i\partial x_j}+\text{<mrow data-mjx-texclass="ORD">lower<mo stretchy="false">−</mo>orderterms</mrow>}=0}$. If ${\displaystyle A=(a_{ij}{)}_{ij}}$ is indefinite such that ${\displaystyle n-1}$ eigenvalues have the same sign and the remaining eigenvalue the other sign, the partial differential equation is called hyperbolic. An example is the wave equation: ${\displaystyle \frac{{\partial }^{2}u}{\partial t^2}-\mathrm{\Delta }u=f}$, where ${\displaystyle \mathrm{\Delta }}$ denotes the Laplace operator, ${\displaystyle u}$ is the unknown, and the function ${\displaystyle f}$ is given.