The "standard implicit" way of determining phase compositions is by means of...

The "standard implicit" way of determining phase compositions is by means of the MiscibleMultiPhaseComposition constraint solver. 
The constraints are written into a matrix and the matrix is solved. 
However, if it cannot be solved an exception is thrown. 
This commit catches that exception, and throws NumericalProblem so the simulation can try and continue. 
- Reviewed by Bernd


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@10030 2fb0f335-1f38-0410-981e-8018bf24f1b0

dumux/material/constraintsolvers/misciblemultiphasecomposition.hh

@@ -162,7 +162,19 @@ public:
         }
 
         // solve for all mole fractions
-        M.solve(x, b);
+        try
+        {
+            M.solve(x, b);
+        }
+        catch (Dune::FMatrixError & e) {
+            DUNE_THROW(NumericalProblem,
+                    "Matrix for composition of phases could not be solved. \n"
+                    "Throwing NumericalProblem for trying with smaller timestep.");
+        }
+        catch (...) {
+            std::cerr << "Unknown exception thrown!\n";
+            exit(1);
+        }
 
         // set all mole fractions and the the additional quantities in
         // the fluid state