tuned fumble parameter EPSILON in BiCGSTABSolver

[[Imported from SVN: r317]]

istl/solvers.hh

@@ -480,7 +480,7 @@ namespace Dune {
     //! apply inverse operator
     virtual void apply (X& x, X& b, InverseOperatorResult& res)
     {
-      const double EPSILON=1e-20;
+      const double EPSILON=1e-40;
 
       int it;
       field_type rho, rho_new, alpha, beta, h, omega;