B-spline B-splines BS methods Cholesky factorization Galerkin method HBVMs Hamiltonian Boundary Value Methods Hamiltonian PDEs Hamiltonian problems Hermite–Obreshkov methods Poisson problems Runge–Kutta THB-splines Volterra integral equations Volterra integro–differential equations adaptive methods analytical solution asymptotic stability barrier options boundary element method collocation method collocation methods conservative problems constrained Hamiltonian problems continuous geometric average convergence curl–curl operator discontinuous Galerkin methods discretization of systems of differential equations displacement rank