4. Operands#
4.1. Operand MATR#
♦ MATR = A,
Name of the system matrix to be solved:
For direct methods, MATR is provided with the concept modified by the FACTORISER operator; this matrix can be real or complex, symmetric or not.
For iterative methods, MATR is provided with the initial matrix. The pre-conditioning matrix is to be provided with the keyword MATR_PREC.
4.2. Operand CHAM_NO#
♦ CHAM_NO = B,
Name of the second member vector (usually obtained by the ASSE_VECTEUR command).
4.3. Operand CHAM_CINE#
◊ CHAM_CINE = vcine,
Name of the vector representing the « value » of the eliminated Dirichlet boundary conditions (i.e. applied with one of the AFFE_CHAR_CINE or AFFE_CHAR_CINE_F commands).
This fiel_no comes from the execution of the operator CALC_CHAR_CINE on the list of char_cine (kinematic loads) associated with the assembled matrix A [U2.01.02].
4.4. Operand ALGORITHME#
◊ ALGORITHME =/'GMRES' [DEFAUT]
/”CG” /”CR” /”GCR”
This keyword is used to choose the algorithm for the iterative method PETSC. The various algorithms available are documented in the keyword SOLVEUR [U4.50.01].
4.5. Operand MATR_PREC#
◊ MATR_PREC = precond
Pre-conditioning matrix, obtained by operator FACTORISER [U4.55.01].
Pre-conditioning is necessary in iterative methods to obtain good convergence with a minimum of iterations.
With method GCPC, the pre-conditioning matrix is a matrix distinct from the problem matrix (keyword MATR).
On the other hand, with method PETSC, we use the same matrix for MATR_PREC and MATR, which means that the command FACTORISER must be done « in place » (with the keyword reuse). See example below.
4.6. Operand RESI_RELA#
◊ RESI_RELA =/1.e-6, [DEFAUT]
/eps, [R]
This keyword is described in [U4.50.01]
For the iterative methods GCPC and PETSC, this is the convergence criterion of the algorithm.
For method MUMPS, this keyword allows you to check the quality of the solution.
4.7. Operand NMAX_ITER#
◊ NMAX_ITER = to rate
Maximum number of iterations of the iterative algorithm.
If niter = 0 then the algorithm chooses a number of iterations by default.
4.8. Operand TITRE#
◊ TITRE = title,
Title that we want to give to the result produced [U4.03.01].
4.9. Operand INFO#
◊ INFO =
1: no printing.
2: impressions