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NEWTON_SOLVER

Specifies nonlinear solver parameters associated with convergence and Jacobian matrix format

Required Cards:

NEWTON_SOLVER <string>
Specifies nonlinear solver for flow or transport (i.e. FLOW or TRANSPORT).

Optional Cards:

NO_INFINITY_NORM
Toggle off calculation of infinity norm on residual and update vectors. The default is to calculate infinity norm.
NO_FORCE_ITERATION
Toggle off the forcing of at least 1 linear iteration. The default is to force at least 1 linear iteration. In a quasi-stationary state, the initial residual may be sufficiently small for convergence, but sometimes it is better to force at least one iteration.
NO_PRINT_CONVERGENCE
Toggle off printing of convergence information.
PRINT_DETAILED_CONVERGENCE
Toggle on printing of detailed convergence information. Warning: this can be a lot of information to parse.

Note: See the PETSc users manual for a more definitive explanation of the solver atol, rtol, and stol tolerances below.

ATOL <float>
Absolute tolerance. Absolute size of 2-norm of residual, i.e.

||f(x_n)|| < ATOL

RTOL <float>
Relative tolerance. Relative decrease in size of 2-norm of residual, i.e.

||f(x_n)||/||f(x_0)|| < RTOL

STOL <float>
Relative update tolerance. Relative decrease in size of 2-norm of solution, i.e.

||x_n-x_(n-1)||/||x_(n-1)-x_(n-2)|| < STOL

ITOL <float>
Infinity tolerance. Size of infinity norm of residual, i.e.

||f(x_n)||_inf < ITOL

ITOL_UPDATE <float>
Infinity tolerance. Size of infinity norm of update, i.e.

||x_n-x_(n-1)||_inf < ITOL_UPDATE

MAXIT <int>
Maximum number of Newton iterations before reporting failed convergence.
MAXF <int>
Maximum number of function evaluations before reporting failed convergence.
MATRIX_TYPE <string>
Format of main solver matrix. PETSc Mat (i.e. AIJ, BAIJ, or HYPRESTRUCT).
PRECONDITIONER_MATRIX_TYPE <string >
Format of preconditioning matrix. PETSc Mat (i.e. AIJ, BAIJ, or HYPRESTRUCT). Default is same as solver.

Examples

NEWTON_SOLVER FLOW
  ITOL_UPDATE 1.d0
/

NEWTON_SOLVER FLOW
  PRECONDITIONER_MATRIX_TYPE AIJ
  RTOL 1.d-8
  ATOL 1.d-8
  STOL 1.d-30
  ITOL_UPDATE 1.d0
/

NEWTON_SOLVER TRANSPORT
  PRECONDITIONER_MATRIX_TYPE AIJ
  RTOL 1.d-12
  ATOL 1.d-12
  STOL 1.d-30
  MAXIT 10
  NO_INFINITY_NORM
  NO_PRINT_CONVERGENCE
/