File snes.hxx#

Functions

BOUT_ENUM_CLASS(BoutSnesEquationForm, pseudo_transient, rearranged_backward_euler, backward_euler, direct_newton)#

class SNESSolver : public Solver #

#include <snes.hxx>

Uses PETSc’s SNES interface to find a steady state solution to a nonlinear ODE by integrating in time with Backward Euler

Public Functions

explicit SNESSolver(Options *opts = nullptr)#

~SNESSolver() = default#

virtual int init() override#: Initialise the solver.

virtual int run() override#

Run the solver, calling monitors nout times, at intervals of tstep. This function is called by solve(), and is specific to each solver type

This should probably be protected, since it shouldn’t be called by users.

PetscErrorCode snes_function(Vec x, Vec f, bool linear)#

Nonlinear function.

Nonlinear function. This is called by PETSc SNES object via a static C-style function. For implicit time integration this function calculates:

f = (x - gamma*G(x)) - rhs

Parameters:

x – [in] The state vector
f – [out] The vector for the result f(x)
linear – [in] Specifies that the SNES solver is in a linear (KSP) inner loop, so the operator should be linearised if possible

PetscErrorCode precon(Vec x, Vec f)#

Preconditioner. Called by PCapply via a C-style static function.

Parameters:

x – [in] The vector to be operated on
f – [out] The result of the operation

Private Members

BoutReal timestep#: Internal timestep.

BoutReal dt#: Current timestep used in snes_function.

BoutReal dt_min_reset#: If dt falls below this, reset solve.

BoutReal max_timestep#: Maximum timestep.

std::string snes_type#

BoutReal atol#: Absolute tolerance.

BoutReal rtol#: Relative tolerance.

BoutReal stol#: Convergence tolerance.

int maxits#: Maximum nonlinear iterations.

int lower_its#

int upper_its#: Limits on iterations for timestep adjustment.

bool diagnose#: Output additional diagnostics.

bool diagnose_failures#: Print diagnostics on SNES failures.

int nlocal#: Number of variables on local processor.

int neq#: Number of variables in total.

BoutSnesEquationForm equation_form#: Form of the equation to solve.

PetscLib lib#: Handles initialising, finalising PETSc.

Vec snes_f#: Used by SNES to store function.

Vec snes_x#: Result of SNES.

Vec x0#: Solution at start of current timestep.

Vec delta_x#: Change in solution.

bool predictor#: Use linear predictor?

Vec x1#: Previous solution.

BoutReal time1 = {-1.0}#: Time of previous solution.

SNES snes#: SNES context.

Mat Jmf#: Matrix-free Jacobian.

MatFDColoring fdcoloring#: Matrix coloring context, used for finite difference Jacobian evaluation

bool use_precon#: Use preconditioner.

std::string ksp_type#: Linear solver type.

bool kspsetinitialguessnonzero#: Set initial guess to non-zero.

int maxl#: Maximum linear iterations.

std::string pc_type#: Preconditioner type.

std::string pc_hypre_type#: Hypre preconditioner type.

std::string line_search_type#: Line search type.

bool matrix_free#: Use matrix free Jacobian.

int lag_jacobian#: Re-use Jacobian.

bool use_coloring#: Use matrix coloring.