Add construction method for solvers

examples/PCGexample.m

@@ -4,7 +4,7 @@
 % ******************************************************************************
 
 %% parameters
-nDofsMax = 1e6;
+nDofsMax = 1e4;
 theta = 0.5;
 pmax = 4; 
 
@@ -31,7 +31,7 @@ for p = 3:pmax
     
     %% set up solver and operator for nested iteration
     P = FeProlongation(fes);
-    solver = JacobiPcgSolver(fes, blf);
+    solver = chooseIterativeSolver(fes, blf, 'pcg', 'jacobi');
     solver.tol = 1e-8;
     solver.maxIter = 100;
     

examples/goafemIterativeSolver.m

@@ -36,7 +36,7 @@ lfG.qrf = QuadratureRule.ofOrder(2*p);
 
 %% set up solver and lifting operator for nested iteration
 P = LoFeProlongation(fes);
-solver = AdditiveSchwartzPcg(P);
+solver = chooseIterativeSolver(fes, blf, 'pcg', 'additiveSchwarz');
 solver.tol = 1e-8;
 solver.maxIter = 1000;
 

examples/goafemMultigrid.m

@@ -38,7 +38,7 @@ lfG.qrf = QuadratureRule.ofOrder(2*p);
 
 %% set up solver and lifting operator for nested iteration
 P = FeProlongation(fes);
-solver = OptimalLocalMGSolver(fes, blf);
+solver = chooseIterativeSolver(fes, blf, 'multigrid');
 solver.tol = 1e-6;
 solver.maxIter = 100;
 

examples/localAdaptiveMultigrid.m

@@ -32,7 +32,7 @@ for p = 1:pmax
     
     %% set up solver and operator for nested iteration
     P = FeProlongation(fes);
-    solver = OptimalLocalMGSolver(fes, blf);
+    solver = chooseIterativeSolver(fes, blf, 'multigrid', 'lowOrderVcycle');
     solver.tol = 1e-8;
     solver.maxIter = 100;
     

lib/solvers/chooseIterativeSolver.m

+% chooseIterativeSolver Return suitable subclass of IterativeSolver.
+
+function solver = chooseIterativeSolver(fes, blf, class, variant)
+arguments
+    fes FeSpace
+    blf BilinearForm
+    class (1,1) string {mustBeMember(class, ["cg", "pcg", "multigrid"])}
+    variant (1,1) string {mustBeMember(variant, [ "", ...
+        "jacobi", "additiveSchwarz", ...
+        "lowOrderVcycle", "highOrderVcycle"])} = ""
+end
+
+switch class
+    % non-preconditioned CG
+    case "cg"
+        solver = CgSolver();
+        
+    % preconditioned CG family
+    case "pcg"
+        switch variant
+            case "jacobi"
+                solver = JacobiPcgSolver(fes, blf);
+            case {"", "additiveSchwarz"}
+                solver = AdditiveSchwartzPcg(fes, blf);
+            otherwise
+                error('No PCG variant %s!', variant)
+        end
+        
+    
+    % geometric multigrid family
+    case "multigrid"
+        switch variant
+            case {"", "lowOrderVcycle"}
+                solver = OptimalLocalMGSolver(fes, blf);
+            case "highOrderVcycle"
+                solver = OptimalLocalMGSolver1pp(fes, blf);
+            otherwise
+                error('No multigrid variant %s!', variant)
+        end
+   
+    % default
+    otherwise
+        error('No iterative solver of class %s!', class)
+end
+    
+end
+
+