gmres solvers improved: householder orthogonalization added; corrections in...

gmres solvers improved: householder orthogonalization added; corrections in sequential PETSc solvers/matrixstreams

AMDiS/CMakeLists.txt

 project(AMDIS)
 
 cmake_minimum_required(VERSION 2.6)
+cmake_policy(SET CMP0017 OLD)
 
 SET(LIB_DIR ${AMDIS_SOURCE_DIR}/lib)
 SET(SOURCE_DIR ${AMDIS_SOURCE_DIR}/src)
@@ -416,7 +417,9 @@ if(ENABLE_EXTENSIONS)
 	      ${EXTENSIONS_DIR}/POperators.cc
 	      ${EXTENSIONS_DIR}/SingularDirichletBC2.cc
 	      ${EXTENSIONS_DIR}/time/ExtendedRosenbrockStationary.cc
-	      ${EXTENSIONS_DIR}/pugixml/src/pugixml.cpp)
+	      ${EXTENSIONS_DIR}/pugixml/src/pugixml.cpp
+	      ${EXTENSIONS_DIR}/preconditioner/PhaseFieldCrystal_.cc
+	      ${EXTENSIONS_DIR}/preconditioner/CahnHilliard_.cc)
 	      
       if(ENABLE_PETSC)
 	list(APPEND EXTENSIONS_SRC
@@ -427,9 +430,7 @@ if(ENABLE_EXTENSIONS)
       if(ENABLE_PARALLEL_DOMAIN)
 	list(APPEND EXTENSIONS_SRC
 # 	      ${EXTENSIONS_DIR}/preconditioner/PetscSolverNavierStokes2.cc
-	      ${EXTENSIONS_DIR}/preconditioner/PetscSolverPfc.cc
-	      ${EXTENSIONS_DIR}/preconditioner/PhaseFieldCrystal_.cc
-	      ${EXTENSIONS_DIR}/preconditioner/CahnHilliard_.cc)
+	      ${EXTENSIONS_DIR}/preconditioner/PetscSolverPfc.cc)
       endif(ENABLE_PARALLEL_DOMAIN)
       
       list(APPEND COMPILEFLAGS "-DHAVE_EXTENSIONS=1")
@@ -708,8 +709,6 @@ list(APPEND deb_add_dirs "share/amdis/doc")
 
 list(REMOVE_DUPLICATES deb_add_dirs)
 
-# TESTING
-
 ENABLE_TESTING()
 INCLUDE(CTest)
 INCLUDE(Dart)

AMDiS/src/BasisFunction.cc

@@ -56,6 +56,7 @@ namespace AMDiS {
 						     const ElementVector& uh_loc, 
 						     WorldMatrix<double>* D2_uh) const
   {
+    // TODO: REMOVE STATIC
     static WorldMatrix<double> D2(DEFAULT_VALUE, 0.0);
     DimMat<double> D2_b(dim, DEFAULT_VALUE, 0.0);
     DimMat<double> D2_tmp(dim, DEFAULT_VALUE, 0.0);

AMDiS/src/CoarseningManager3d.cc

@@ -296,7 +296,7 @@ namespace AMDiS {
   {
     FUNCNAME_DBG("CoarseningManager3d::getCoarsenPatch()");
 
-    static unsigned char next_el[6][2] = {{3,2},
+    static const unsigned char next_el[6][2] = {{3,2},
 					  {1,3},
 					  {1,2},
 					  {0,3},

AMDiS/src/DOFVector.cc

@@ -531,7 +531,7 @@ namespace AMDiS {
     DOFAdmin *admin = feSpace->getAdmin();
 
     // define result vector
-    static WorldVector<DOFVector<double>*> *result = nullptr;
+    static WorldVector<DOFVector<double>*> *result = nullptr; // TODO: REMOVE STATIC
 
     if (grad) {
       result = grad;
@@ -630,7 +630,7 @@ namespace AMDiS {
     TEST_EXIT_DBG(vec)("no vector\n");
 
     int dow = Global::getGeo(WORLD);
-    static WorldVector<DOFVector<double>*> *result = nullptr;
+    static WorldVector<DOFVector<double>*> *result = nullptr; // TODO: REMOVE STATIC
 
     if (!res && !result) {
       result = new WorldVector<DOFVector<double>*>;

AMDiS/src/DOFVector.hh

@@ -1247,15 +1247,15 @@ namespace AMDiS {
   template<typename T>
   const DOFVector<T>& operator*(const DOFVector<T>& v, double d)
   {
-    static DOFVector<T> result;
-    return mult(d, v, result);
+    static DOFVector<T> result; // TODO: REMOVE STATIC
+    return mult(d, v, result); 
   }
 
 
   template<typename T>
   const DOFVector<T>& operator*(double d, const DOFVector<T>& v)
   {
-    static DOFVector<T> result;
+    static DOFVector<T> result; // TODO: REMOVE STATIC
     return mult(d, v, result);
   }
 
@@ -1263,7 +1263,7 @@ namespace AMDiS {
   template<typename T>
   const DOFVector<T>& operator+(const DOFVector<T> &v1 , const DOFVector<T> &v2)
   {
-    static DOFVector<T> result;
+    static DOFVector<T> result; // TODO: REMOVE STATIC
     return add(v1, v2, result);
   }
 
@@ -1765,7 +1765,7 @@ namespace AMDiS {
     const FiniteElemSpace *feSpace = DOFVector<T>::feSpace;
 
     // define result vector
-    static DOFVector<typename GradientType<T>::type> *result = nullptr;
+    static DOFVector<typename GradientType<T>::type> *result = nullptr; // TODO: REMOVE STATIC
 
     if (grad) {
       result = grad;
@@ -1850,7 +1850,7 @@ namespace AMDiS {
     int dim = DOFVector<T>::dim;
 
     // define result vector
-    static DOFVector<typename GradientType<T>::type> *vec = nullptr;
+    static DOFVector<typename GradientType<T>::type> *vec = nullptr; // TODO: REMOVE STATIC
 
     DOFVector<typename GradientType<T>::type> *result = grad;
 
@@ -1922,7 +1922,7 @@ namespace AMDiS {
 
     TEST_EXIT_DBG(vec)("no vector\n");
 
-    static std::vector<DOFVector<double>*> *result = nullptr;
+    static std::vector<DOFVector<double>*> *result = nullptr; // TODO: REMOVE STATIC
 
     int len = num_rows(GradientType<T>::getValues((*vec)[0]));
     

AMDiS/src/Recovery.cc

@@ -795,7 +795,7 @@ Recovery::recoveryUh(DOFVector<double> *uh, const FiniteElemSpace *fe_space)
   }
   
   // define result vector
-  static DOFVector<double> *vec = nullptr;
+  static DOFVector<double> *vec = nullptr;// TODO: REMOVE STATIC
   DOFVector<double> *result = nullptr;
 
   // Allocate memory for result vector
@@ -868,7 +868,7 @@ Recovery::recovery(DOFVector<double> *uh, const FiniteElemSpace *fe_space,
   }
 
   // define result vector
-  static DOFVector<WorldVector<double> > *vec = nullptr;
+  static DOFVector<WorldVector<double> > *vec = nullptr;// TODO: REMOVE STATIC
   DOFVector<WorldVector<double> > *result = nullptr;
 
   // Allocate memory for result vector
@@ -920,7 +920,7 @@ Recovery::recovery(DOFVector<double> *uh,
   const FiniteElemSpace *fe_space = uh->getFeSpace();
 
   // define result vector
-  static DOFVector<WorldVector<double> > *vec = nullptr;
+  static DOFVector<WorldVector<double> > *vec = nullptr;// TODO: REMOVE STATIC
   DOFVector<WorldVector<double> > *result = nullptr;
 
   // Allocate memory for result vector

AMDiS/src/Tetrahedron.cc

@@ -131,6 +131,7 @@ namespace AMDiS {
 
   void Tetrahedron::sortFaceIndices(int face, FixVec<int,WORLD> &vec) const
   {
+    // TODO: REMOVE STATIC
     static MatrixOfFixVecs<FixVec<int,WORLD> > *sorted_3d = nullptr;
 
     if (sorted_3d == nullptr) {

AMDiS/src/Tetrahedron.h

@@ -66,7 +66,7 @@ namespace AMDiS {
 
     virtual int getPositionOfVertex(int side, int vertex) const 
     {
-      static int positionOfVertex[4][4] = {{-1, 0, 1, 2},
+      static const int positionOfVertex[4][4] = {{-1, 0, 1, 2},
 					   {0, -1, 1, 2},
 					   {0, 1, -1, 2},
 					   {0, 1, 2, -1}};

AMDiS/src/Traverse.cc

@@ -536,6 +536,7 @@ namespace AMDiS {
     int sav_neighbour = neighbour;
 
     // father.neigh[coarse_nb[i][j]] == child[i - 1].neigh[j]
+    // TODO: REMOVE STATIC
     static int coarse_nb[3][3][4] = {{{-2, -2, -2, -2}, {-1, 2, 3, 1}, {-1, 3, 2, 0}},
 				     {{-2, -2, -2, -2}, {-1, 2, 3, 1}, {-1, 2, 3, 0}},
 				     {{-2, -2, -2, -2}, {-1, 2, 3, 1}, {-1, 2, 3, 0}}};
@@ -799,6 +800,7 @@ namespace AMDiS {
     int sav_neighbour = neighbour;
 
     // father.neigh[coarse_nb[i][j]] == child[i-1].neigh[j]
+    // TODO: REMOVE STATIC
     static int coarse_nb[3][3] = {{-2, -2, -2}, {2, -1, 1}, {-1, 2, 0}};
 
     TEST_EXIT_DBG(stack_used > 0)("no current element");

AMDiS/src/Triangle.cc

@@ -62,6 +62,7 @@ namespace AMDiS {
 
   void Triangle::sortFaceIndices(int face, FixVec<int, WORLD> &vec) const
   {
+    // TODO: REMOVE STATIC
     static MatrixOfFixVecs<FixVec<int, WORLD> > *sorted_2d = nullptr;
 
     if (sorted_2d == nullptr) {

AMDiS/src/Triangle.h

@@ -160,7 +160,7 @@ namespace AMDiS {
       TEST_EXIT_DBG(side >= 0 && side <= 2)("Wrong side number %d!\n", side);
       TEST_EXIT_DBG(vertex >= 0 && vertex <= 2)("Wrong vertex number %d!\n", vertex);
 
-      static int positionOfVertex[3][3] = {{-1, 0, 1}, {1, -1, 0}, {0, 1, -1}};
+      static const int positionOfVertex[3][3] = {{-1, 0, 1}, {1, -1, 0}, {0, 1, -1}};
       return positionOfVertex[side][vertex];
     }
 

AMDiS/src/io/DofWriter.cc

@@ -52,7 +52,8 @@ namespace AMDiS {
     
     ofstream outfile;
     outfile.open(filename.c_str());
-    outfile.precision(10);
+    outfile.setf( std::ios::scientific, std:: ios::floatfield );
+    outfile.precision(16);
     
     DOFIterator<WorldVector<double> > it(&coordDof, USED_DOFS);
     for (it.reset(); !it.end(); ++it) {

AMDiS/src/parallel/PetscSolverNavierStokes.cc

@@ -144,7 +144,7 @@ namespace AMDiS { namespace Parallel {
     int dim = componentSpaces[pressureComponent]->getMesh()->getDim();
 
     vector<int> velocityComponents;
-    for (size_t i = 0; i < dim; i++)
+    for (int i = 0; i < dim; i++)
       velocityComponents.push_back(i);
 
     PCSetType(pc, PCFIELDSPLIT);

AMDiS/src/solver/ITL_Solver.h

@@ -41,7 +41,9 @@
 #include "solver/itl/minres.hpp"
 #include "solver/itl/gcr.hpp"
 #include "solver/itl/fgmres.hpp"
+#include "solver/itl/fgmres_householder.hpp"
 #include "solver/itl/gmres2.hpp"
+#include "solver/itl/gmres_householder.hpp"
 #include "solver/itl/preonly.hpp"
 
 
@@ -264,20 +266,37 @@ namespace AMDiS {
    * The method is not preconditioned 
    */
   
+  enum ORTHOGONALIZATION {
+    GRAM_SCHMIDT = 1,
+    HOUSEHOLDER = 2
+  };
+  
   class gmres_type
   {
-    int restart;
+    int restart; 
+    ORTHOGONALIZATION orthogonalization;
+    
   public:
-    gmres_type(std::string name) : restart(30)
+    gmres_type(std::string name) : restart(30), orthogonalization(GRAM_SCHMIDT)
     {
       Parameters::get(name + "->restart", restart);
+      Parameters::get(name + "->orthogonalization", orthogonalization);
     }
     template < class LinOp, class X, class B, class L, class R, class I >
     int operator()(const LinOp& A, X& x, const B& b, const L& l, const R& r, I& iter)
-    { return itl::gmres2(A, x, b, l, r, iter, restart); }
+    { 
+      switch (orthogonalization) {
+	default:
+	case GRAM_SCHMIDT:
+	  return itl::gmres2(A, x, b, l, r, iter, restart); break;
+	case HOUSEHOLDER:
+	  return itl::gmres_householder(A, x, b, l, iter, restart); break;
+      }
+    }
   };
   typedef ITL_Solver< gmres_type > GMResSolver;
 
+  
   // ===================================================================================
 
   /**  
@@ -343,6 +362,7 @@ namespace AMDiS {
   class gcr_type
   {
     int restart;
+    
   public:
     gcr_type(std::string name) : restart(30)
     {
@@ -369,14 +389,25 @@ namespace AMDiS {
   class fgmres_type
   {
     int restart;
+    ORTHOGONALIZATION orthogonalization;
+    
   public:
-    fgmres_type(std::string name) : restart(30)
+    fgmres_type(std::string name) : restart(30), orthogonalization(GRAM_SCHMIDT)
     {
       Parameters::get(name + "->restart", restart);
+      Parameters::get(name + "->orthogonalization", orthogonalization);
     }
     template < class LinOp, class X, class B, class L, class R, class I >
     int operator()(const LinOp& A, X& x, const B& b, const L& l, const R& r, I& iter)
-    { return itl::fgmres(A, x, b, l, r, iter, restart); }
+    {
+      switch (orthogonalization) {
+	default:
+	case GRAM_SCHMIDT:
+	  return itl::fgmres(A, x, b, l, r, iter, restart); break;
+	case HOUSEHOLDER:
+	  return itl::fgmres_householder(A, x, b, r, iter, restart); break;
+      }
+    }
   };
   typedef ITL_Solver< fgmres_type > FGMResSolver;
 

AMDiS/src/solver/KrylovPreconditioner.h

@@ -67,15 +67,15 @@ namespace AMDiS {
     KrylovPreconditioner(std::string name) : fullMatrix(nullptr), solver(nullptr), runner(nullptr)
     {
 
-  #if defined HAVE_PARALLEL_PETSC
+#if defined HAVE_PARALLEL_PETSC
       string backend("p_petsc");
-  #elif defined HAVE_PARALLEL_MTL
+#elif defined HAVE_PARALLEL_MTL
       string backend("p_mtl");
-  #elif defined HAVE_PETSC
+#elif defined HAVE_PETSC
       string backend("petsc");
-  #else
+#else
       string backend("mtl");
-  #endif
+#endif
       
       // === read backend-name ===
       string initFileStr = name + "->solver";    

AMDiS/src/solver/MatrixStreams.h

@@ -240,7 +240,11 @@ namespace AMDiS {
   /// fill PETSc vector from DOFVector
   inline void operator<<(Vec& petscVec, /* const */SystemVector& vec)
   {
-    const VecType vecType; // TODO: type changed from petsc 3.2 to petsc 3.3
+#ifdef VecType // PETSc uses MACROS instead of typedefs in Versions 3.3x
+    const VecType vecType;
+#else
+    VecType vecType;
+#endif
     VecGetType(petscVec, &vecType);
     
     if (strcmp(vecType, VECNEST) == 0) {
@@ -265,7 +269,11 @@ namespace AMDiS {
   /// fill SystemVector from PETSc vector
   inline void operator>>(const Vec& petscVec, SystemVector& vec)
   {
+#ifdef VecType // PETSc uses MACROS instead of typedefs in Versions 3.3x
     const VecType vecType;
+#else
+    VecType vecType;
+#endif
     VecGetType(petscVec, &vecType);
     
     if (strcmp(vecType, VECNEST) == 0) {

AMDiS/src/solver/itl/fgmres_householder.hpp

+/******************************************************************************
+ *
+ * AMDiS - Adaptive multidimensional simulations
+ *
+ * Copyright (C) 2013 Dresden University of Technology. All Rights Reserved.
+ * Web: https://fusionforge.zih.tu-dresden.de/projects/amdis
+ *
+ * Authors: 
+ * Simon Vey, Thomas Witkowski, Andreas Naumann, Simon Praetorius, et al.
+ *
+ * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+ * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ *
+ * This file is part of AMDiS
+ *
+ * See also license.opensource.txt in the distribution.
+ * 
+ ******************************************************************************/
+
+// Written by Simon Praetorius (adopted from previous implementation)
+
+
+#ifndef ITL_FGMRES_HOUSEHOLDER_INCLUDE
+#define ITL_FGMRES_HOUSEHOLDER_INCLUDE
+
+#include <algorithm>
+#include <boost/numeric/mtl/concept/collection.hpp>
+#include <boost/numeric/mtl/vector/dense_vector.hpp>
+#include <boost/numeric/mtl/matrix/dense2D.hpp>
+#include <boost/numeric/mtl/matrix/multi_vector.hpp>
+#include <boost/numeric/mtl/operation/givens.hpp>
+#include <boost/numeric/mtl/operation/two_norm.hpp>
+#include <boost/numeric/mtl/utility/exception.hpp>
+#include <boost/numeric/mtl/utility/irange.hpp>
+
+#include "solver/itl/details.hpp"
+
+namespace itl {
+
+/// Flexible Generalized Minimal Residual method (without restart) using householder othogonalization
+/** It computes at most kmax_in iterations (or size(x) depending on what is smaller) 
+    regardless on whether the termination criterion is reached or not.   **/
+template < typename Matrix, typename Vector, typename RightPreconditioner, typename Iteration >
+int fgmres_householder_full(const Matrix &A, Vector &x, const Vector &b,
+               RightPreconditioner &R, Iteration& iter)
+{
+    using mtl::irange; using std::abs; using math::reciprocal; using mtl::iall; using mtl::imax;
+    using mtl::signum; using mtl::vector::dot; using mtl::conj;
+    typedef typename mtl::Collection<Vector>::value_type Scalar;
+    typedef typename mtl::Collection<Vector>::size_type  Size;
+
+    if (size(b) == 0) throw mtl::logic_error("empty rhs vector");
+
+    const Scalar zero= math::zero(Scalar()), dbl_tol= 1.e-16;
+    Scalar       rho, bnrm2, temp, alpha, beta;
+    Size         k, kmax(std::min(size(x), Size(iter.max_iterations() - iter.iterations())));
+    Vector       w(solve(R, b)), r(b - A*x);
+    mtl::matrix::multi_vector<Vector>   V(Vector(resource(x), zero), kmax+1); 
+    mtl::matrix::multi_vector<Vector>   Z(Vector(resource(x), zero), kmax+1); 
+    mtl::vector::dense_vector<Scalar>   sn(kmax, zero), cs(kmax, zero), s(kmax+1, zero), y(kmax, zero);  // replicated in distributed solvers 
+    mtl::matrix::dense2D<Scalar>        H(kmax, kmax);
+
+    
+    
+    bnrm2 = two_norm(w);
+    if (bnrm2 < dbl_tol)
+      bnrm2 = 1.0;
+    // TODO: if rhs=0 => solution=0 ??
+    
+    temp = two_norm(r);				// norm of preconditioned residual
+    rho = temp * reciprocal(bnrm2);
+    if (iter.finished(rho))			// initial guess is good enough solution
+      return iter;
+    
+    // u = r + sing(r(0))*||r||*e0
+    beta = signum(r[0])*temp;
+    w = r;
+    w[0] += beta;
+    w *= reciprocal(two_norm(w));
+    
+    V.vector(0) = w;
+    H = zero;
+    s[0] = -beta;
+
+    // GMRES iteration
+    for (k= 0; k < kmax && !iter.finished(rho); ++k, ++iter) {
+      
+      w = (-2.0 * V.vector(k)[k])*V.vector(k);
+      w[k] += 1.0;
+      // v := P_0*...*P_{k-2}*(P_{k-1} * e_k)
+      for (Size i= k; i > 0; i--) {
+	temp = 2.0 * dot(V.vector(i-1), w);
+	w -= temp * V.vector(i-1);
+      }
+      
+      temp = two_norm(w);
+      if (temp == zero)
+	return iter.fail(2, "GMRES: breakdown");
+      
+      // Explicitly normalize v to reduce the effects of round-off.
+      Z.vector(k) = solve(R, w);
+      w = A * Z.vector(k);
+      
+      // P_{k-1}*...*P_0*Av
+      for (Size i = 0; i <= k; i++) {
+	temp = 2.0 * dot(V.vector(i), w);
+	w -= temp * V.vector(i);
+      }
+      
+      temp = two_norm(w);
+      if (temp == zero)
+	return iter.fail(3, "GMRES: breakdown");
+      
+      irange range_to_end(k+1,imax);
+      set_to_zero(V.vector(k+1));
+      V.vector(k+1)[range_to_end] = w[range_to_end];
+      alpha = two_norm(V.vector(k+1));
+      if (alpha != 0.0) {
+	alpha *= signum(w[k+1]);
+	V.vector(k+1)[k+1] += alpha;
+	V.vector(k+1) *= reciprocal(two_norm(V.vector(k+1)));
+	
+	w[k+1] = -alpha;
+      }
+      
+      for (Size i= 0; i < k; i++) {
+	temp   =  conj(cs[i])*w[i] + conj(sn[i])*w[i+1];
+	w[i+1] =- sn[i]*w[i] + cs[i]*w[i+1];
+	w[i]   =  temp;
+      }
+      
+      details::rotmat(w[k], w[k+1], cs[k], sn[k]);
+      
+      s[k+1] = -sn[k]*s[k];
+      s[k]   = conj(cs[k])*s[k];
+      w[k] = cs[k]*w[k] + sn[k]*w[k+1];
+      w[k+1] = 0.0;
+      
+      irange range(num_rows(H));
+      H[iall][k] = w[range];
+      
+      rho = std::abs(s[k+1]) / bnrm2;
+    }
+        
+    // reduce k, to get regular matrix
+//     while (k > 0 && std::abs(s[k-1]) <= iter.atol()) k--;
+
+    // iteration is finished -> compute x: solve H*y=s as far as rank of H allows
+    irange range(k);
+    for (; !range.empty(); --range) {
+      try {
+	  y[range] = upper_trisolve(H[range][range], s[range]); 
+      } catch (mtl::matrix_singular) { continue; } // if singular then try with sub-matrix
+      break;
+    }
+
+    if (range.finish() < k)
+  	std::cerr << "GMRES orhogonalized with " << k << " vectors but matrix singular, can only use " 
+		  << range.finish() << " vectors!\n";
+    if (range.empty())
+        return iter.fail(3, "GMRES did not find any direction to correct x");
+    
+
+    x += Z.vector(range) * y[range];
+    
+    r = b - A*x;
+    return iter.terminate(r);
+}
+
+/// Felxible Generalized Minimal Residual method with restart
+template < typename Matrix, typename Vector,
+           typename RightPreconditioner, typename Iteration >
+int fgmres_householder(const Matrix &A, Vector &x, const Vector &b,
+          RightPreconditioner &R,
+	  Iteration& iter, typename mtl::Collection<Vector>::size_type restart)
+{   
+  do {
+    Iteration inner(iter);
+    inner.set_max_iterations(std::min(int(iter.iterations()+restart), iter.max_iterations()));
+    inner.suppress_resume(true);
+    fgmres_householder_full(A, x, b, R, inner);
+    iter.update_progress(inner);
+  } while (!iter.finished());
+
+  return iter;
+}
+
+
+
+} // namespace itl
+
+#endif // ITL_FGMRES_HOUSEHOLDER_INCLUDE
+
+

AMDiS/src/solver/itl/gmres2.hpp

@@ -62,10 +62,11 @@ int gmres2_full(const Matrix &A, Vector &x, const Vector &b,
     bnrm2 = two_norm(b);
     if (bnrm2 < dbl_tol)
       bnrm2 = 1.0;
+    // TODO: if rhs=0 => solution=0 ??
     
-    temp = two_norm(r);
+    temp = two_norm(r);				// norm of preconditioned residual
     rho = temp * reciprocal(bnrm2);
-    if (iter.finished(rho))
+    if (iter.finished(rho))			// initial guess is good enough solution
       return iter;
     
     V.vector(0) = r * reciprocal(temp);
@@ -78,7 +79,7 @@ int gmres2_full(const Matrix &A, Vector &x, const Vector &b,
       r = A * Vector(solve(R, V.vector(k)));
       w = solve(L, r);
       temp = two_norm(w);
-      
+            
       // orth(V, w, false); 
       // modified Gram Schmidt method
       for (Size i= 0; i < k+1; i++) {

AMDiS/src/solver/itl/gmres_householder.hpp

+/******************************************************************************
+ *
+ * AMDiS - Adaptive multidimensional simulations
+ *
+ * Copyright (C) 2013 Dresden University of Technology. All Rights Reserved.
+ * Web: https://fusionforge.zih.tu-dresden.de/projects/amdis
+ *
+ * Authors: 
+ * Simon Vey, Thomas Witkowski, Andreas Naumann, Simon Praetorius, et al.
+ *
+ * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+ * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *