DEigensystem

DEigensystem[ℒ[u[x, y, ...]], u, {x, y, ...} ∈ Ω, n] gives the n smallest magnitude eigenvalues and eigenfunctions for the linear differential operator ℒ over the region Ω.

DEigensystem[eqns, u, t, {x, y, ...} ∈ Ω, n] gives the eigenvalues and eigenfunctions for solutions u of the time-dependent differential equations eqns.

Examples

Find eigenvalues and eigenfunctions:

DEigensystem[-Laplacian[u[x, y], {x, y}], u, {x, y} ∈ Rectangle[], 3]

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