Given integral functionals Φ1,,Φm\Phi_1,\ldots,\Phi_m on a class of functions, moment matching asks for uu such that

Φj(u)=dj,1jm.\Phi_j(u)=d_j,\qquad 1\le j\le m.

The moment map in this sense is Φ(u)=(Φ1(u),,Φm(u))\Phi(u)=(\Phi_1(u),\ldots,\Phi_m(u)). The functionals may be linear or integrals of nonlinear expressions such as u2u^2.

Function-valued targets

For profiles u(r,η)u(r,\eta), one may prescribe Φj(u)(η)=dj(η)\Phi_j(u)(\eta)=d_j(\eta) for every η\eta. There are finitely many rows, but each row is a function. Solving at finitely many sample values does not establish this identity. Corrections built from fixed radial bumps and parameter-dependent coefficients reduce the problem to a parameterized finite system. This integral moment map is distinct from a Hamiltonian moment map in symplectic geometry.