#include "petscmat.h" PetscErrorCode MatCreateMFFD(MPI_Comm comm,PetscInt m,PetscInt n,PetscInt M,PetscInt N,Mat *J)Collective on Vec Many br
comm | - MPI communicator Many br | |
m | - number of local rows (or PETSC_DECIDE to have calculated if M is given) Many brThis value should be the same as the local size used in creating the Many bry vector for the matrix-vector product y = Ax. Many br | |
n | - This value should be the same as the local size used in creating the Many brx vector for the matrix-vector product y = Ax. (or PETSC_DECIDE to have Many brcalculated if N is given) For square matrices n is almost always m. Many br | |
M | - number of global rows (or PETSC_DETERMINE to have calculated if m is given) Many br | |
N | - number of global columns (or PETSC_DETERMINE to have calculated if n is given) Many br |
Options Database Keys: call MatSetFromOptions() to trigger these Many br
-mat_mffd_type | - wp or ds (see MATMFFD_WP or MATMFFD_DS) Many br | |
-mat_mffd_err | - square root of estimated relative error in function evaluation Many br |
Many br
The default code uses the following approach to compute h Many br
F'(u)*a = [F(u+h*a) - F(u)]/h where h = error_rel*u'a/||a||^2 if |u'a| > umin*||a||_{1} = error_rel*umin*sign(u'a)*||a||_{1}/||a||^2 otherwise where error_rel = square root of relative error in function evaluation umin = minimum iterate parameterMany br
You can call SNESSetJacobian() with MatMFFDComputeJacobian() if you are using matrix and not a different Many brpreconditioner matrix Many br
The user can set the error_rel via MatMFFDSetFunctionError() and Many brumin via MatMFFDDSSetUmin(); see Users-Manual: ch_snes for details. Many br
The user should call MatDestroy() when finished with the matrix-free Many brmatrix context. Many br
-mat_mffd_err <error_rel> | - Sets error_rel Many br | |
-mat_mffd_unim <umin> | - Sets umin (for default PETSc routine that computes h only) Many br | |
-mat_mffd_check_positivity | - Many br |
Level:advanced
Location:src/mat/impls/mffd/mffd.c
Index of all Mat routines
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Index of all manual pages