3. Operands#
The choice of the resolution method is made beforehand in the NUME_DDL command (keyword METHODE).
Five methods are possible: “MULT_FRONT”, “MUMPS”, “”, “GCPC”, “PETSC” and “LDLT”.
3.1. Keyword reuse = matas#
For the sake of simplifying programming and also to save disk space, the factorization « in place » of the matrix (use of reuse) is generally mandatory.
The exception is the pair (“GCPC”, “LDLT_INC”). In this case, it is forbidden to use reuse.
3.2. Operand MATR_ASSE#
♦ MATR_ASSE = matt
Name of the assembled matrix to be factored or pre-conditioned according to the method.
For the “LDLT”, “MULT_FRONT” and “MUMPS” methods, this matrix can be real or complex, symmetric or not. On the other hand, for the “GCPC” and “PETSC” methods, this matrix must be real. For “GCPC”, the matrix must also be symmetric.
Operands STOP_SINGULIER, NPREC, TYPE_RESOL, PCENT_PIVOT, PRETRAITEMENTS,,,, GESTION_MEMOIRE,, ACCELERATION, LOW_RANK_SEUIL,,,,,, PRE_COND NIVE_REMPLISSAGE REMPLISSAGE RENUM REAC_PRECOND ELIM_LAGR ————————————— ———-
These keywords are described in [U4.50.01].
3.3. Operand TITRE#
◊ TITRE = title
Title we want to give to the result [U4.02.01].
3.4. Operand INFO#
◊ INFO =
1: no printing
3.5. Partial factorization (method LDLT)#
For the “LDLT” method, the operator allows the matrix to be factored only partially. This possibility makes it possible to factor the matrix in several times (several jobs) or even to modify the last rows of this factored matrix on the fly. Today, this functionality is of little interest except for certain (so-called discrete) methods of contact and friction where the terms concerning the nodes likely to be in contact have been deliberately placed in the last rows of the matrix. Thus, as the matching iterations progress, the relationships between these nodes change, we erase and then recalculate only these last contributions of the factored ones. This is a typical example where the clever use of a rather frustrating algorithm can lead to major gains (in time).
◊/BLOC_DEBUT = bd
bd: partial factorization from the bd-th block inclusive.
/DDL_DEBUT = dd
dd: partial factorization from the tenth equation included (with internal numbering established by the operator NUME_DDL [U4.61.11]).
◊/BLOC_FIN = bf
bf: partial factorization up to and including the bf-th block.
/DDL_FIN = df
df: partial factorization up to and including the df-th equation (with internal numbering established by the operator NUME_DDL [U4.61.11]).
BLOC_DEBUT and DDL_DEBUT
in the absence of the keywords BLOC_DEBUT and DDL_DEBUT, the matrix will be factored from its first line.
if the bd argument of the BLOC_DEBUT keyword is negative or zero, the matrix will be factored from the first block. Otherwise, a partial factorization is performed starting from the bd-th block inclusive.
if the dd argument of the DDL_DEBUT keyword is negative or zero, the matrix will be factored from the first equation. Otherwise, a partial factorization is performed using the d-th equation included.
