/IMPL/SOLVER

Engine Keyword Selects linear solver.

Format

/IMPL/SOLVER/N

Iprec It_max Itol Tol

Definitions

Field Contents SI Unit Example
N Linear solver method number (solve Ax=b).
= 0
Set to 1.
= 1
Iterative solver. Preconditioned Conjugate Gradient (PCG).
= 2
Direct solver MUMPS.
= 3
Direct
  • SMP: Boeing Solver (BCS).
  • SPMD: Massively parallel multi-frontal solver (MUMPS).
= 5
Mix
Two solvers will be used at same time. For instance, in SMP case, two solvers BCS and PCG will be used at same time.
  • SMP: BCS and PCG (Iprec =5).
  • SPMD: MUMPS and PCG (Iprec =5).
= 7
Auto. 4
  • Select automatic between solver direct and PCG (Iprec =5).
  
Iprec Precondition methods.
= 0
Set to 5.
= 1
No preconditioner.
= 2
Diagonal Jacobi.
= 5
Factored approximate inverse.
  
It_max Maximum iteration number used for stop criteria.
= 0 or > NDOF
Set to NDOF (system dimension).
  
Itol Stop criteria for Preconditioned iterative solver flag.
= 0
Set to 3.
= 1
Relative Residual of original matrix (residual r = A x − b , ‖ r ‖ < T o l * ‖ b ‖ MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8akY=xipgYlh9vqqj=hEeei0xXdbb a9frFf0=yqFf0dbba91qpepeI8k8fiI+fsY=rqaqpepae9pg0Firpe pesP0xe9Fve9Fve9qapdbaGaaiGadiWaamaaceGaaqaacaqbaaGcba GaamOCaiabg2da9iaadgeacaWG4bGaeyOeI0IaamOyaiaacYcadaqb diqaaiaadkhaaiaawMa7caGLkWoacqGH8aapcaWGubGaam4BaiaadY gacaGGQaWaauWaceaacaWGIbaacaGLjWUaayPcSdaaaa@4CBA@ ).
= 2
Relative Residual of preconditioned matrix ( ‖ r ‖ < T o l * ‖ b ' ‖ MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8akY=xipgYlh9vqqj=hEeei0xXdbb a9frFf0=yqFf0dbba91qpepeI8k8fiI+fsY=rqaqpepae9pg0Firpe pesP0xe9Fve9Fve9qapdbaGaaiGadiWaamaaceGaaqaacaqbaaGcba WaauWaceaacaWGYbaacaGLjWUaayPcSdGaeyipaWJaamivaiaad+ga caWGSbGaaiOkamaafmGabaGaamOyaiaacEcaaiaawMa7caGLkWoaaa a@4721@ ).
= 3
Relative Residual of preconditioned matrix ( ‖ r ‖ < T o l * ‖ b ' ‖ * ‖ A ' ‖ * ‖ x ‖ MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbwvMCKf MBHbqefqvATv2CG4uz3bIuV1wyUbqedmvETj2BSbqefm0B1jxALjhi ov2DaebbnrfifHhDYfgasaacH8akY=xipgYlh9vqqj=hEeei0xXdbb a9frFf0=yqFf0dbba91qpepeI8k8fiI+fsY=rqaqpepae9pg0Firpe pesP0xe9Fve9Fve9qapdbaGaaiGadiWaamaaceGaaqaacaqbaaGcba WaauWaceaacaWGYbaacaGLjWUaayPcSdGaeyipaWJaamivaiaad+ga caWGSbGaaiOkamaafmGabaGaamOyaiaacEcaaiaawMa7caGLkWoaca GGQaWaauWaceaacaWGbbGaai4jaaGaayzcSlaawQa7aiaacQcadaqb diqaaiaadIhaaiaawMa7caGLkWoaaaa@513D@ ).
  
Tol Input tolerance for stop criteria.
= 0.0
Set to 1.0e-5, if Itol =1 or 2 set to machine simple precision, if Itol =3.
  

Comments

  1. When this keyword is not defined, all default values will be used.
  2. Linear solvers are also used in nonlinear iterations. When /IMPL/NONLIN is used, the linear solver parameters, rather than default values can be defined in this keyword.
  3. For Direct solvers (N=3), or Mix solver (N=5), mono-thread (nt=1) has been recommended for versions prior to 13.0; BCS is being used with mono-domain and MUMPS is used for multi-domain (np > 1).
  4. N=5 (Mix):

    Two solvers will be used at same time. For instance, in SMP case, two solvers BCS and PCG will be used at same time.

    N=7 (Auto):

    PCG as the basic solver will be used first. It will factorize coefficient matrix (which is done by direct solver) and it is used as a pre-conditioner. The solver will be changed automatically to direct solver, if PCG performance is estimated slower than Direct solver. In this case, Direct solver will be used for the remainder of the run.

  5. Mix and Auto solvers are used for nonlinear implicit analysis.