In the theory of partial differential equations, elliptic operators are differential operators that generalize the Laplace operator. They are defined by the condition that the coefficients of the highest-order derivatives be positive, which implies the key property that the principal symbol is invertible, or equivalently that there are no real characteristic directions.
Elliptic operators are typical of potential theory, and they appear frequently in electrostatics and continuum mechanics. Elliptic regularity implies that their solutions tend to be smooth functions (if the coefficients in the operator are smooth). Steady-state solutions to hyperbolic and parabolic equations generally solve elliptic equations.
of partial differential equations, ellipticoperators are differential operators that generalize the Laplace operator. They are defined by the condition...
the Laplacian operator has been used for various tasks, such as blob and edge detection. The Laplacian is the simplest ellipticoperator and is at the...
well-behaved comprises the pseudo-differential operators. The differential operator P {\displaystyle P} is elliptic if its symbol is invertible; that is for...
papers from 1968 to 1971. Instead of just one ellipticoperator, one can consider a family of ellipticoperators parameterized by some space Y. In this case...
linear partial differential equations (PDEs) are classified as either elliptic, hyperbolic, or parabolic. Any second-order linear PDE in two variables...
with an ellipticoperator An elliptic partial differential equation This disambiguation page lists articles associated with the title Elliptic equation...
are other ways to prove this.) Indeed, the operators Δ are elliptic, and the kernel of an ellipticoperator on a closed manifold is always a finite-dimensional...
multi-dimensional parabolic PDE. Noting that − Δ {\displaystyle -\Delta } is an ellipticoperator suggests a broader definition of a parabolic PDE: u t = − L u , {\displaystyle...
opposite of this winding number. Any ellipticoperator can be extended to a Fredholm operator. The use of Fredholm operators in partial differential equations...
data. The argument goes as follows. A typical simple-to-understand ellipticoperator L would be the Laplacian plus some lower order terms. Combined with...
of differential operator involved. For an ellipticoperator, one discusses elliptic boundary value problems. For a hyperbolic operator, one discusses hyperbolic...
differential geometry there are a number of second-order, linear, elliptic differential operators bearing the name Laplacian. This article provides an overview...
Here, L stands for a linear differential operator. For example, one might take L to be an ellipticoperator, such as L = d 2 d x 2 {\displaystyle L={\frac...
constraints in Hamiltonian mechanics Regularity of an ellipticoperator Regularity theory of elliptic partial differential equations Regular algebra, or...
that for the ordinary Poisson problem. In general, to each scalar ellipticoperator L of order 2k, there is associated a bilinear form B on the Sobolev...
L} is said to be elliptic when a b > 0 {\displaystyle ab>0} and hyperbolic if a b < 0 {\displaystyle ab<0} . Similarly, the operator L = D x + D y 2 {\displaystyle...
frequently admits all of these interpretations, as follows. Given an ellipticoperator L , {\displaystyle L,} the parabolic PDE u t = L u {\displaystyle...
spectral properties then follow from the theory of compact operators; in particular, an elliptic boundary value problem on a bounded domain has infinitely...
semigroups theory: for instance, if A is a symmetric matrix, then the ellipticoperator defined by A u ( x ) := ∑ i , j ∂ x i a i j ( x ) ∂ x j u ( x ) {\displaystyle...
energy functionals in the calculus of variations. Solutions to a uniformly elliptic partial differential equation with divergence form ∇ ⋅ ( A ∇ u ) = 0 {\displaystyle...
determinants, making the divergent constants cancel. Let S be an elliptic differential operator with smooth coefficients which is positive on functions of compact...