gf_precond

Synopsis

PC = gf_precond('identity')
PC = gf_precond('cidentity')
PC = gf_precond('diagonal', vec D)
PC = gf_precond('ildlt', spmat m)
PC = gf_precond('ilu', spmat m)
PC = gf_precond('ildltt', spmat m[, int fillin[, scalar threshold]])
PC = gf_precond('ilut', spmat m[, int fillin[, scalar threshold]])
PC = gf_precond('superlu', spmat m)
PC = gf_precond('spmat', spmat m)

Description :

General constructor for precond objects.

The preconditioners may store REAL or COMPLEX values. They accept getfem sparse matrices and Matlab sparse matrices.

Command list :

PC = gf_precond('identity')

Create a REAL identity precondioner.

PC = gf_precond('cidentity')

Create a COMPLEX identity precondioner.

PC = gf_precond('diagonal', vec D)

Create a diagonal precondioner.

PC = gf_precond('ildlt', spmat m)

Create an ILDLT (Cholesky) preconditioner for the (symmetric) sparse matrix <literal>m</literal>. This preconditioner has the same sparsity pattern than <literal>m</literal> (no fill-in).

PC = gf_precond('ilu', spmat m)

Create an ILU (Incomplete LU) preconditioner for the sparse matrix <literal>m</literal>. This preconditioner has the same sparsity pattern than <literal>m</literal> (no fill-in).

PC = gf_precond('ildltt', spmat m[, int fillin[, scalar threshold]])

Create an ILDLTT (Cholesky with filling) preconditioner for the (symmetric) sparse matrix <literal>m</literal>. The preconditioner may add at most <literal>fillin</literal> additional non-zero entries on each line. The default value for <literal>fillin</literal> is 10, and the default threshold is1e-7.

PC = gf_precond('ilut', spmat m[, int fillin[, scalar threshold]])

Create an ILUT (Incomplete LU with filling) preconditioner for the sparse matrix <literal>m</literal>. The preconditioner may add at most <literal>fillin</literal> additional non-zero entries on each line. The default value for <literal>fillin</literal> is 10, and the default threshold is 1e-7.

PC = gf_precond('superlu', spmat m)

Uses SuperLU to build an exact factorization of the sparse matrix <literal>m</literal>. This preconditioner is only available if the getfem-interface was built with SuperLU support. Note that LU factorization is likely to eat all your memory for 3D problems.

PC = gf_precond('spmat', spmat m)

Preconditionner given explicitely by a sparse matrix.