Revert "[solvers] add identity as precoditioner"

This reverts commit 6ccda57b8891f355b575590d5f12a5cf9eaf2ecb.

[[Imported from SVN: r1672]]

dune/istl/preconditioners.hh

@@ -128,62 +128,6 @@ namespace Dune {
   // Implementation of this interface for sequential ISTL-preconditioners
   //=====================================================================
 
-  /*!
-     \brief Dummy preconditioner class which does nothing, i.e. uses the identity as preconditioner
-
-     \tparam M The matrix type to operate on
-     \tparam X Type of the update
-     \tparam Y Type of the defect
-     \tparam l The block level to invert. Default is 1
-   */
-  template<class M, class X, int l=1>
-  class IdentityPrec : public Preconditioner<X,X> {
-  public:
-    //! \brief The matrix type the preconditioner is for.
-    typedef M matrix_type;
-    //! \brief The domain type of the preconditioner.
-    typedef X domain_type;
-    //! \brief The range type of the preconditioner.
-    typedef X range_type;
-    //! \brief The field type of the preconditioner.
-    typedef typename X::field_type field_type;
-
-    // define the category
-    enum {
-      //! \brief The category the preconditioner is part of.
-      category=SolverCategory::sequential
-    };
-
-    /*! \brief Constructor does not need any arguments as the preconditioner does nothing.    */
-    IdentityPrec() {}
-
-    /*!
-       \brief Prepare the preconditioner.
-
-       \copydoc Preconditioner::pre(X&,Y&)
-     */
-    virtual void pre (X& x, X& b) {}
-
-    /*!
-       \brief Apply the preconditioner
-
-       \copydoc Preconditioner::apply(X&,const Y&)
-     */
-    virtual void apply (X& v, const X& d)
-    {
-      v = d;
-    }
-
-    /*!
-       \brief Clean up.
-
-       \copydoc Preconditioner::post(X&)
-     */
-    virtual void post (X& x) {}
-
-  private:
-  };
-
 
   /*!
      \brief Sequential SSOR preconditioner.