Tolerate linear solver failure in non-linear schemes

Author: lhy11009

.vscode/launch.json

@@ -2,35 +2,22 @@
     "version": "0.2.0",
     "configurations": [
         {
-            "name": "(gdb) Launch",
+            "name": "C++ Launch",
             "type": "cppdbg",
             "request": "launch",
             // Resolved by CMake Tools:
-            "program": "${command:cmake.launchTargetPath}",
+            "program": "${workspaceFolder}/build/aspect-debug",
 	    // *** replace --test by the name of the .prm file you want to run: ***
-            "args": ["--test"],
+            "args": ["TwoDSubduction_skip_expensive_stokes.prm"],
             "stopAtEntry": true,
 	    // *** append to the path here if you want to run inside some directory like /cookbooks/ ***
-            "cwd": "${workspaceFolder}",
+            "cwd": "/home/lochy/Softwares/aspect/dtemp",
             "environment": [
                 {
                     // add the directory where our target was built to the PATHs
                     // it gets resolved by CMake Tools:
-                    "name": "PATH",
-                    "value": "${env:PATH}:${command:cmake.getLaunchTargetDirectory}"
-                },
-                {
-                    "name": "OTHER_VALUE",
-                    "value": "Something something"
-                }
-            ],
-            "externalConsole": false,
-            "MIMode": "gdb",
-            "setupCommands": [
-                {
-                    "description": "Enable pretty-printing for gdb",
-                    "text": "-enable-pretty-printing",
-                    "ignoreFailures": true
+                    "name": "config",
+                    "value": "Debug"
                 }
             ]
         }

include/aspect/parameters.h

@@ -549,6 +549,8 @@ namespace aspect
      */
     typename NonlinearSolver::Kind nonlinear_solver;
     typename NonlinearSolverFailureStrategy::Kind nonlinear_solver_failure_strategy;
+    // todo_solver
+    bool continue_nonlinear_solver_loop_after_linear_solver_failure;
 
     typename AdvectionStabilizationMethod::Kind advection_stabilization_method;
     double                         nonlinear_tolerance;

source/simulator/newton.cc

@@ -185,7 +185,7 @@ namespace aspect
                              "true, the derivatives are slowly introduced by the following equation: $\\max(0.0, "
                              "(1.0-(residual/switch\\_initial\\_residual)))$, where switch\\_initial\\_residual is the "
                              "residual at the time when the Newton solver is switched on.");
-
+          
           prm.declare_entry ("Maximum linear Stokes solver tolerance", "1e-2",
                              Patterns::Double (0., 1.),
                              "The linear Stokes solver tolerance is dynamically chosen for the Newton solver, based "

source/simulator/parameters.cc

@@ -283,6 +283,14 @@ namespace aspect
                        "This parameter is only relevant if the `Nonlinear solver scheme' does nonlinear "
                        "iterations, in other words, if it is set to something other than "
                        "`single Advection, single Stokes' or `single Advection, no Stokes'.");
+          
+                       // todo_solver
+          prm.declare_entry ("Continue nonlinear solver loop after linear solver failure", "false",
+                             Patterns::Bool (),
+                             "This method allows to continue nonlinear solver loop after linear solver fails "
+                             "If set to false, the linear solver failure is thrown as normally. When this is "
+                             "set to true, the failure is tolerated and the nonlinear solver continues with "
+                             "the next linear solve.");
 
     prm.declare_entry ("Pressure normalization", "surface",
                        Patterns::Selection ("surface|volume|no"),
@@ -1611,6 +1619,8 @@ namespace aspect
     }
     nonlinear_solver_failure_strategy = NonlinearSolverFailureStrategy::parse(
                                           prm.get("Nonlinear solver failure strategy"));
+    // todo_solver
+    continue_nonlinear_solver_loop_after_linear_solver_failure = prm.get_bool("Continue nonlinear solver loop after linear solver failure");
 
     prm.enter_subsection ("Solver parameters");
     {

source/simulator/solver_schemes.cc

@@ -682,6 +682,8 @@ namespace aspect
         // We get here if the Stokes solve above failed. Let's see first
         // why that happened:
 
+        // todo_solver
+
         // If the exception we got is not one of the two documented by
         // throw_linear_solver_failure_exception(), then we have a genuine
         // problem here, and will need to get outta here right away: