PARTIAL DIFFERENTIAL EQUATIONS - Math
web.math.princeton.edu › ~seri › homepage• Can add and multiply uand its partial derivatives between themselves as well as with given functions of the variables x. Composition with given functions may also appear. In the case of the equation (1) the associated differential operator is P = ∆ = ∂2 1 + ∂ 2 2 + ∂ 3 = P 3 i,j=1 e ij∂ i∂ j where eij is the diagonal 3 × 3 matrix with entries
Computational Physics Lectures: Partial differential equations
compphysics.github.io › ComputationalPhysics › docFamous PDEs, Helmholtz' equation Other famous partial differential equations are the Helmholtz (or eigenvalue) equation, here specialized to two dimensions only $$ \begin{equation} \label{eq:helmholtz} -\frac{\partial^2 u}{\partial x^2}-\frac{\partial^2 u}{\partial y^2}=\lambda u, \end{equation} $$ the linear transport equation (in \( 2+1 \) dimensions) familiar from Brownian motion as well $$ \begin{equation} \label{eq:transport} \frac{\partial u}{\partial t} +\frac{\partial u}{\partial x ...