Levenberg-Marquardt no catches exceptions due to singular Hessian

nonlin.cpp

@@ -353,9 +353,17 @@ NonlinOut levmar(const NonlinParam& p, const NonlinCF& cfo)
         H->AddTo(i,i,p.Lambda()-olambda);             
       }
     }
-    ColumnVector step = -H->SolveForx(g,SYM_POSDEF,p.EquationSolverTol(),p.EquationSolverMaxIter());
-    double ncf = cfo.cf(p.Par()+step);
-    if (success = (ncf < p.CF())) {                           // If last step successful
+    ColumnVector step;
+    double ncf = 0.0;
+    bool inv_fail = false;  // Signals failure of equation solving
+    try {
+      step = -H->SolveForx(g,SYM_POSDEF,p.EquationSolverTol(),p.EquationSolverMaxIter());
+      ncf = cfo.cf(p.Par()+step);
+    }
+    catch(...) {
+      inv_fail = true;
+    }
+    if (!inv_fail && (success = (ncf < p.CF()))) {              // If last step successful
       olambda = 0.0;                                          // Pristine Hessian, so no need to undo old lambda
       p.SetPar(p.Par()+step);                                 // Set attempt as new parameters
       p.SetLambda(p.Lambda()/10.0);                           // Decrease nudge factor