The article is an in-depth comparison of numerical solvers and corresponding solution processes of the systems of algebraic equations resulting from finite difference, collocation, and finite element approximations. The paper considers recently developed isogeometric versions of the collocation and finite element methods, employing B-splines for the computations and ensuring C p−1 continuity on the borders of elements for the B-splines of the order p. For solving the systems, we use our GPU implementation of the state-of-the-art parallel multifrontal solver, which leverages modern GPU architectures and allows to reduce the complexity. We analyze the structures of linear equation systems resulting from each of the methods and how different matrix structures lead to different multifrontal solver elimination trees. The paper also considers the flows of multifrontal solver depending on the originally employed method.
Background and motivationEssentially, each of the analyzed methods (finite difference method (FDM), collocation, finite element method (FEM)) yields a system of linear algebraic equations. The system is then passed to a solver -either sequential or parallel. The paper focuses on our GPU implementation of the state-of-the-art parallel multifrontal solver as described in [5,6,7,8,9], featuring logarithmic computational complexity with respect to the size of the matrix.The paper compares the structure of the matrices generated by 1D FDM, collocation method and FEM and the corresponding forward elimination trees built within the solver. We have not found such a holistic comparison in the existing literature. We believe such a comparison may be of benefit to the researchers who deal with direct solvers and isogeometric analysis. We firstly derive the system of linear algebraic equations and multifrontal solver trees for FDM and FEM with hierarchical basis functions [3] and then switch to isogeometric bases.