OOF2: The Manual

Name

LinearSolver — Solution methods for linear matrix equations.

Subclasses

Subclasses are listed as they appear in the GUI and (in parentheses) as they appear in scripts.

  • CG (CGSolver) -- Conjugate Gradient method for solving symmetric matrices.
  • GMRES (GMRESSolver) -- Generalized Minimal Residual method. An iterative method for non-symmetric matrices.
  • BiCG (BiCGSolver) -- Bi-Conjugate Gradient method. An iterative method for non-symmetric matrices.
  • BiCGStab (BiCGStabSolver) -- Stabilized Bi-Conjugate Gradient method for non-symmetric matrices.
  • Direct (DirectSolver) -- A non-iterative non-sparse matrix solver using LU decomposition. Uses a lot of memory. Not recommended if the finite element mesh is large.

Description

LinearSolvers are applied by Drivers to solve the linear matrix equations that arise when solving Equations on a Mesh.

The different types of LinearSolver are applicable to different types of matrix equations. The reference page for each subclass gives some information about its applicability. In particular, solution methods for symmetric matrices can take advantage of the symmetry to obtain a solution more efficiently. OOF2 constructs symmetric matrices when possible, and only allows the symmetric solver (CGSolver) to be used in those cases.

The matrices that arise in finite element calculations are generally sparse, meaning that many of their entries are zero. Sparse matrices can be stored efficiently by only retaining the non-zero values. The iterative LinearSolvers have the advantageous property of not requiring storage for the full matrix. DirectSolver solvers, on the other hand, generate intermediate values at all matrix entries, and so their storage requirements are much larger.


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