Squashed 'third_party/eigen/' changes from 61d72f6..cf794d3


Change-Id: I9b814151b01f49af6337a8605d0c42a3a1ed4c72
git-subtree-dir: third_party/eigen
git-subtree-split: cf794d3b741a6278df169e58461f8529f43bce5d
diff --git a/test/sparse_solver.h b/test/sparse_solver.h
index 59d77da..5145bc3 100644
--- a/test/sparse_solver.h
+++ b/test/sparse_solver.h
@@ -9,102 +9,167 @@
 
 #include "sparse.h"
 #include <Eigen/SparseCore>
+#include <sstream>
+
+template<typename Solver, typename Rhs, typename Guess,typename Result>
+void solve_with_guess(IterativeSolverBase<Solver>& solver, const MatrixBase<Rhs>& b, const Guess& g, Result &x) {
+  if(internal::random<bool>())
+  {
+    // With a temporary through evaluator<SolveWithGuess>
+    x = solver.derived().solveWithGuess(b,g) + Result::Zero(x.rows(), x.cols());
+  }
+  else
+  {
+    // direct evaluation within x through Assignment<Result,SolveWithGuess>
+    x = solver.derived().solveWithGuess(b.derived(),g);
+  }
+}
+
+template<typename Solver, typename Rhs, typename Guess,typename Result>
+void solve_with_guess(SparseSolverBase<Solver>& solver, const MatrixBase<Rhs>& b, const Guess& , Result& x) {
+  if(internal::random<bool>())
+    x = solver.derived().solve(b) + Result::Zero(x.rows(), x.cols());
+  else
+    x = solver.derived().solve(b);
+}
+
+template<typename Solver, typename Rhs, typename Guess,typename Result>
+void solve_with_guess(SparseSolverBase<Solver>& solver, const SparseMatrixBase<Rhs>& b, const Guess& , Result& x) {
+  x = solver.derived().solve(b);
+}
 
 template<typename Solver, typename Rhs, typename DenseMat, typename DenseRhs>
 void check_sparse_solving(Solver& solver, const typename Solver::MatrixType& A, const Rhs& b, const DenseMat& dA, const DenseRhs& db)
 {
   typedef typename Solver::MatrixType Mat;
   typedef typename Mat::Scalar Scalar;
+  typedef typename Mat::StorageIndex StorageIndex;
 
-  DenseRhs refX = dA.lu().solve(db);
+  DenseRhs refX = dA.householderQr().solve(db);
   {
-    Rhs x(b.rows(), b.cols());
+    Rhs x(A.cols(), b.cols());
     Rhs oldb = b;
 
     solver.compute(A);
     if (solver.info() != Success)
     {
-      std::cerr << "sparse solver testing: factorization failed (check_sparse_solving)\n";
-      exit(0);
-      return;
+      std::cerr << "ERROR | sparse solver testing, factorization failed (" << typeid(Solver).name() << ")\n";
+      VERIFY(solver.info() == Success);
     }
     x = solver.solve(b);
     if (solver.info() != Success)
     {
-      std::cerr << "sparse solver testing: solving failed\n";
+      std::cerr << "WARNING | sparse solver testing: solving failed (" << typeid(Solver).name() << ")\n";
       return;
     }
     VERIFY(oldb.isApprox(b) && "sparse solver testing: the rhs should not be modified!");
-
     VERIFY(x.isApprox(refX,test_precision<Scalar>()));
+
+    x.setZero();
+    solve_with_guess(solver, b, x, x);
+    VERIFY(solver.info() == Success && "solving failed when using analyzePattern/factorize API");
+    VERIFY(oldb.isApprox(b) && "sparse solver testing: the rhs should not be modified!");
+    VERIFY(x.isApprox(refX,test_precision<Scalar>()));
+    
     x.setZero();
     // test the analyze/factorize API
     solver.analyzePattern(A);
     solver.factorize(A);
-    if (solver.info() != Success)
-    {
-      std::cerr << "sparse solver testing: factorization failed (check_sparse_solving)\n";
-      exit(0);
-      return;
-    }
+    VERIFY(solver.info() == Success && "factorization failed when using analyzePattern/factorize API");
     x = solver.solve(b);
-    if (solver.info() != Success)
-    {
-      std::cerr << "sparse solver testing: solving failed\n";
-      return;
-    }
+    VERIFY(solver.info() == Success && "solving failed when using analyzePattern/factorize API");
     VERIFY(oldb.isApprox(b) && "sparse solver testing: the rhs should not be modified!");
-
     VERIFY(x.isApprox(refX,test_precision<Scalar>()));
+    
+    x.setZero();
+    // test with Map
+    MappedSparseMatrix<Scalar,Mat::Options,StorageIndex> Am(A.rows(), A.cols(), A.nonZeros(), const_cast<StorageIndex*>(A.outerIndexPtr()), const_cast<StorageIndex*>(A.innerIndexPtr()), const_cast<Scalar*>(A.valuePtr()));
+    solver.compute(Am);
+    VERIFY(solver.info() == Success && "factorization failed when using Map");
+    DenseRhs dx(refX);
+    dx.setZero();
+    Map<DenseRhs> xm(dx.data(), dx.rows(), dx.cols());
+    Map<const DenseRhs> bm(db.data(), db.rows(), db.cols());
+    xm = solver.solve(bm);
+    VERIFY(solver.info() == Success && "solving failed when using Map");
+    VERIFY(oldb.isApprox(bm) && "sparse solver testing: the rhs should not be modified!");
+    VERIFY(xm.isApprox(refX,test_precision<Scalar>()));
   }
   
-  // test dense Block as the result and rhs:
+  // if not too large, do some extra check:
+  if(A.rows()<2000)
   {
-    DenseRhs x(db.rows(), db.cols());
-    DenseRhs oldb(db);
-    x.setZero();
-    x.block(0,0,x.rows(),x.cols()) = solver.solve(db.block(0,0,db.rows(),db.cols()));
-    VERIFY(oldb.isApprox(db) && "sparse solver testing: the rhs should not be modified!");
-    VERIFY(x.isApprox(refX,test_precision<Scalar>()));
+    // test initialization ctor
+    {
+      Rhs x(b.rows(), b.cols());
+      Solver solver2(A);
+      VERIFY(solver2.info() == Success);
+      x = solver2.solve(b);
+      VERIFY(x.isApprox(refX,test_precision<Scalar>()));
+    }
+
+    // test dense Block as the result and rhs:
+    {
+      DenseRhs x(refX.rows(), refX.cols());
+      DenseRhs oldb(db);
+      x.setZero();
+      x.block(0,0,x.rows(),x.cols()) = solver.solve(db.block(0,0,db.rows(),db.cols()));
+      VERIFY(oldb.isApprox(db) && "sparse solver testing: the rhs should not be modified!");
+      VERIFY(x.isApprox(refX,test_precision<Scalar>()));
+    }
+
+    // test uncompressed inputs
+    {
+      Mat A2 = A;
+      A2.reserve((ArrayXf::Random(A.outerSize())+2).template cast<typename Mat::StorageIndex>().eval());
+      solver.compute(A2);
+      Rhs x = solver.solve(b);
+      VERIFY(x.isApprox(refX,test_precision<Scalar>()));
+    }
+
+    // test expression as input
+    {
+      solver.compute(0.5*(A+A));
+      Rhs x = solver.solve(b);
+      VERIFY(x.isApprox(refX,test_precision<Scalar>()));
+
+      Solver solver2(0.5*(A+A));
+      Rhs x2 = solver2.solve(b);
+      VERIFY(x2.isApprox(refX,test_precision<Scalar>()));
+    }
   }
 }
 
 template<typename Solver, typename Rhs>
-void check_sparse_solving_real_cases(Solver& solver, const typename Solver::MatrixType& A, const Rhs& b, const Rhs& refX)
+void check_sparse_solving_real_cases(Solver& solver, const typename Solver::MatrixType& A, const Rhs& b, const typename Solver::MatrixType& fullA, const Rhs& refX)
 {
   typedef typename Solver::MatrixType Mat;
   typedef typename Mat::Scalar Scalar;
   typedef typename Mat::RealScalar RealScalar;
   
-  Rhs x(b.rows(), b.cols());
-  
+  Rhs x(A.cols(), b.cols());
+
   solver.compute(A);
   if (solver.info() != Success)
   {
-    std::cerr << "sparse solver testing: factorization failed (check_sparse_solving_real_cases)\n";
-    exit(0);
-    return;
+    std::cerr << "ERROR | sparse solver testing, factorization failed (" << typeid(Solver).name() << ")\n";
+    VERIFY(solver.info() == Success);
   }
   x = solver.solve(b);
+  
   if (solver.info() != Success)
   {
-    std::cerr << "sparse solver testing: solving failed\n";
+    std::cerr << "WARNING | sparse solver testing, solving failed (" << typeid(Solver).name() << ")\n";
     return;
   }
   
-  RealScalar res_error;
-  // Compute the norm of the relative error
-  if(refX.size() != 0)
-    res_error = (refX - x).norm()/refX.norm();
-  else
-  { 
-    // Compute the relative residual norm
-    res_error = (b - A * x).norm()/b.norm();
-  }
-  if (res_error > test_precision<Scalar>() ){
-    std::cerr << "Test " << g_test_stack.back() << " failed in "EI_PP_MAKE_STRING(__FILE__) 
-    << " (" << EI_PP_MAKE_STRING(__LINE__) << ")" << std::endl << std::endl;
-    abort();
+  RealScalar res_error = (fullA*x-b).norm()/b.norm();  
+  VERIFY( (res_error <= test_precision<Scalar>() ) && "sparse solver failed without noticing it"); 
+
+  
+  if(refX.size() != 0 && (refX - x).norm()/refX.norm() > test_precision<Scalar>())
+  {
+    std::cerr << "WARNING | found solution is different from the provided reference one\n";
   }
   
 }
@@ -117,7 +182,7 @@
   solver.compute(A);
   if (solver.info() != Success)
   {
-    std::cerr << "sparse solver testing: factorization failed (check_sparse_determinant)\n";
+    std::cerr << "WARNING | sparse solver testing: factorization failed (check_sparse_determinant)\n";
     return;
   }
 
@@ -134,7 +199,7 @@
   solver.compute(A);
   if (solver.info() != Success)
   {
-    std::cerr << "sparse solver testing: factorization failed (check_sparse_abs_determinant)\n";
+    std::cerr << "WARNING | sparse solver testing: factorization failed (check_sparse_abs_determinant)\n";
     return;
   }
 
@@ -181,13 +246,33 @@
     mat_folder = mat_folder + static_cast<std::string>("/real/");
   return mat_folder;
 }
+std::string sym_to_string(int sym)
+{
+  if(sym==Symmetric) return "Symmetric ";
+  if(sym==SPD)       return "SPD ";
+  return "";
+}
+template<typename Derived>
+std::string solver_stats(const IterativeSolverBase<Derived> &solver)
+{
+  std::stringstream ss;
+  ss << solver.iterations() << " iters, error: " << solver.error();
+  return ss.str();
+}
+template<typename Derived>
+std::string solver_stats(const SparseSolverBase<Derived> &/*solver*/)
+{
+  return "";
+}
 #endif
 
-template<typename Solver> void check_sparse_spd_solving(Solver& solver)
+template<typename Solver> void check_sparse_spd_solving(Solver& solver, int maxSize = 300, int maxRealWorldSize = 100000)
 {
   typedef typename Solver::MatrixType Mat;
   typedef typename Mat::Scalar Scalar;
-  typedef SparseMatrix<Scalar,ColMajor> SpMat;
+  typedef typename Mat::StorageIndex StorageIndex;
+  typedef SparseMatrix<Scalar,ColMajor, StorageIndex> SpMat;
+  typedef SparseVector<Scalar, 0, StorageIndex> SpVec;
   typedef Matrix<Scalar,Dynamic,Dynamic> DenseMatrix;
   typedef Matrix<Scalar,Dynamic,1> DenseVector;
 
@@ -195,7 +280,7 @@
   Mat A, halfA;
   DenseMatrix dA;
   for (int i = 0; i < g_repeat; i++) {
-    int size = generate_sparse_spd_problem(solver, A, halfA, dA);
+    int size = generate_sparse_spd_problem(solver, A, halfA, dA, maxSize);
 
     // generate the right hand sides
     int rhsCols = internal::random<int>(1,16);
@@ -204,13 +289,17 @@
     DenseVector b = DenseVector::Random(size);
     DenseMatrix dB(size,rhsCols);
     initSparse<Scalar>(density, dB, B, ForceNonZeroDiag);
+    SpVec c = B.col(0);
+    DenseVector dc = dB.col(0);
   
-    check_sparse_solving(solver, A,     b,  dA, b);
-    check_sparse_solving(solver, halfA, b,  dA, b);
-    check_sparse_solving(solver, A,     dB, dA, dB);
-    check_sparse_solving(solver, halfA, dB, dA, dB);
-    check_sparse_solving(solver, A,     B,  dA, dB);
-    check_sparse_solving(solver, halfA, B,  dA, dB);
+    CALL_SUBTEST( check_sparse_solving(solver, A,     b,  dA, b)  );
+    CALL_SUBTEST( check_sparse_solving(solver, halfA, b,  dA, b)  );
+    CALL_SUBTEST( check_sparse_solving(solver, A,     dB, dA, dB) );
+    CALL_SUBTEST( check_sparse_solving(solver, halfA, dB, dA, dB) );
+    CALL_SUBTEST( check_sparse_solving(solver, A,     B,  dA, dB) );
+    CALL_SUBTEST( check_sparse_solving(solver, halfA, B,  dA, dB) );
+    CALL_SUBTEST( check_sparse_solving(solver, A,     c,  dA, dc) );
+    CALL_SUBTEST( check_sparse_solving(solver, halfA, c,  dA, dc) );
     
     // check only once
     if(i==0)
@@ -221,25 +310,44 @@
   }
   
   // First, get the folder 
-#ifdef TEST_REAL_CASES  
-  if (internal::is_same<Scalar, float>::value 
-      || internal::is_same<Scalar, std::complex<float> >::value)
-    return ;
-  
-  std::string mat_folder = get_matrixfolder<Scalar>();
-  MatrixMarketIterator<Scalar> it(mat_folder);
-  for (; it; ++it)
+#ifdef TEST_REAL_CASES
+  // Test real problems with double precision only
+  if (internal::is_same<typename NumTraits<Scalar>::Real, double>::value)
   {
-    if (it.sym() == SPD){
-      Mat halfA;
-      PermutationMatrix<Dynamic, Dynamic, Index> pnull;
-      halfA.template selfadjointView<Solver::UpLo>() = it.matrix().template triangularView<Eigen::Lower>().twistedBy(pnull);
-      
-      std::cout<< " ==== SOLVING WITH MATRIX " << it.matname() << " ==== \n";
-      check_sparse_solving_real_cases(solver, it.matrix(), it.rhs(), it.refX());
-      check_sparse_solving_real_cases(solver, halfA, it.rhs(), it.refX());
+    std::string mat_folder = get_matrixfolder<Scalar>();
+    MatrixMarketIterator<Scalar> it(mat_folder);
+    for (; it; ++it)
+    {
+      if (it.sym() == SPD){
+        A = it.matrix();
+        if(A.diagonal().size() <= maxRealWorldSize)
+        {
+          DenseVector b = it.rhs();
+          DenseVector refX = it.refX();
+          PermutationMatrix<Dynamic, Dynamic, StorageIndex> pnull;
+          halfA.resize(A.rows(), A.cols());
+          if(Solver::UpLo == (Lower|Upper))
+            halfA = A;
+          else
+            halfA.template selfadjointView<Solver::UpLo>() = A.template triangularView<Eigen::Lower>().twistedBy(pnull);
+          
+          std::cout << "INFO | Testing " << sym_to_string(it.sym()) << "sparse problem " << it.matname()
+                  << " (" << A.rows() << "x" << A.cols() << ") using " << typeid(Solver).name() << "..." << std::endl;
+          CALL_SUBTEST( check_sparse_solving_real_cases(solver, A,     b, A, refX) );
+          std::string stats = solver_stats(solver);
+          if(stats.size()>0)
+            std::cout << "INFO |  " << stats << std::endl;
+          CALL_SUBTEST( check_sparse_solving_real_cases(solver, halfA, b, A, refX) );
+        }
+        else
+        {
+          std::cout << "INFO | Skip sparse problem \"" << it.matname() << "\" (too large)" << std::endl;
+        }
+      }
     }
   }
+#else
+  EIGEN_UNUSED_VARIABLE(maxRealWorldSize);
 #endif
 }
 
@@ -261,27 +369,39 @@
 }
 
 template<typename Solver, typename DenseMat>
-int generate_sparse_square_problem(Solver&, typename Solver::MatrixType& A, DenseMat& dA, int maxSize = 300)
+Index generate_sparse_square_problem(Solver&, typename Solver::MatrixType& A, DenseMat& dA, int maxSize = 300, int options = ForceNonZeroDiag)
 {
   typedef typename Solver::MatrixType Mat;
   typedef typename Mat::Scalar Scalar;
 
-  int size = internal::random<int>(1,maxSize);
+  Index size = internal::random<int>(1,maxSize);
   double density = (std::max)(8./(size*size), 0.01);
   
   A.resize(size,size);
   dA.resize(size,size);
 
-  initSparse<Scalar>(density, dA, A, ForceNonZeroDiag);
+  initSparse<Scalar>(density, dA, A, options);
   
   return size;
 }
 
-template<typename Solver> void check_sparse_square_solving(Solver& solver)
+
+struct prune_column {
+  Index m_col;
+  prune_column(Index col) : m_col(col) {}
+  template<class Scalar>
+  bool operator()(Index, Index col, const Scalar&) const {
+    return col != m_col;
+  }
+};
+
+
+template<typename Solver> void check_sparse_square_solving(Solver& solver, int maxSize = 300, int maxRealWorldSize = 100000, bool checkDeficient = false)
 {
   typedef typename Solver::MatrixType Mat;
   typedef typename Mat::Scalar Scalar;
-  typedef SparseMatrix<Scalar,ColMajor> SpMat;
+  typedef SparseMatrix<Scalar,ColMajor, typename Mat::StorageIndex> SpMat;
+  typedef SparseVector<Scalar, 0, typename Mat::StorageIndex> SpVec;
   typedef Matrix<Scalar,Dynamic,Dynamic> DenseMatrix;
   typedef Matrix<Scalar,Dynamic,1> DenseVector;
 
@@ -290,7 +410,7 @@
   Mat A;
   DenseMatrix dA;
   for (int i = 0; i < g_repeat; i++) {
-    int size = generate_sparse_square_problem(solver, A, dA);
+    Index size = generate_sparse_square_problem(solver, A, dA, maxSize);
 
     A.makeCompressed();
     DenseVector b = DenseVector::Random(size);
@@ -299,9 +419,12 @@
     double density = (std::max)(8./(size*rhsCols), 0.1);
     initSparse<Scalar>(density, dB, B, ForceNonZeroDiag);
     B.makeCompressed();
-    check_sparse_solving(solver, A, b,  dA, b);
-    check_sparse_solving(solver, A, dB, dA, dB);
-    check_sparse_solving(solver, A, B,  dA, dB);
+    SpVec c = B.col(0);
+    DenseVector dc = dB.col(0);
+    CALL_SUBTEST(check_sparse_solving(solver, A, b,  dA, b));
+    CALL_SUBTEST(check_sparse_solving(solver, A, dB, dA, dB));
+    CALL_SUBTEST(check_sparse_solving(solver, A, B,  dA, dB));
+    CALL_SUBTEST(check_sparse_solving(solver, A, c,  dA, dc));
     
     // check only once
     if(i==0)
@@ -309,21 +432,44 @@
       b = DenseVector::Zero(size);
       check_sparse_solving(solver, A, b, dA, b);
     }
+    // regression test for Bug 792 (structurally rank deficient matrices):
+    if(checkDeficient && size>1) {
+      Index col = internal::random<int>(0,int(size-1));
+      A.prune(prune_column(col));
+      solver.compute(A);
+      VERIFY_IS_EQUAL(solver.info(), NumericalIssue);
+    }
   }
   
   // First, get the folder 
 #ifdef TEST_REAL_CASES
-  if (internal::is_same<Scalar, float>::value 
-      || internal::is_same<Scalar, std::complex<float> >::value)
-    return ;
-  
-  std::string mat_folder = get_matrixfolder<Scalar>();
-  MatrixMarketIterator<Scalar> it(mat_folder);
-  for (; it; ++it)
+  // Test real problems with double precision only
+  if (internal::is_same<typename NumTraits<Scalar>::Real, double>::value)
   {
-    std::cout<< " ==== SOLVING WITH MATRIX " << it.matname() << " ==== \n";
-    check_sparse_solving_real_cases(solver, it.matrix(), it.rhs(), it.refX());
+    std::string mat_folder = get_matrixfolder<Scalar>();
+    MatrixMarketIterator<Scalar> it(mat_folder);
+    for (; it; ++it)
+    {
+      A = it.matrix();
+      if(A.diagonal().size() <= maxRealWorldSize)
+      {
+        DenseVector b = it.rhs();
+        DenseVector refX = it.refX();
+        std::cout << "INFO | Testing " << sym_to_string(it.sym()) << "sparse problem " << it.matname()
+                  << " (" << A.rows() << "x" << A.cols() << ") using " << typeid(Solver).name() << "..." << std::endl;
+        CALL_SUBTEST(check_sparse_solving_real_cases(solver, A, b, A, refX));
+        std::string stats = solver_stats(solver);
+        if(stats.size()>0)
+          std::cout << "INFO |  " << stats << std::endl;
+      }
+      else
+      {
+        std::cout << "INFO | SKIP sparse problem \"" << it.matname() << "\" (too large)" << std::endl;
+      }
+    }
   }
+#else
+  EIGEN_UNUSED_VARIABLE(maxRealWorldSize);
 #endif
 
 }
@@ -333,13 +479,20 @@
   typedef typename Solver::MatrixType Mat;
   typedef typename Mat::Scalar Scalar;
   typedef Matrix<Scalar,Dynamic,Dynamic> DenseMatrix;
-
-  // generate the problem
-  Mat A;
-  DenseMatrix dA;
-  generate_sparse_square_problem(solver, A, dA, 30);
-  A.makeCompressed();
+  
   for (int i = 0; i < g_repeat; i++) {
+    // generate the problem
+    Mat A;
+    DenseMatrix dA;
+    
+    int size = internal::random<int>(1,30);
+    dA.setRandom(size,size);
+    
+    dA = (dA.array().abs()<0.3).select(0,dA);
+    dA.diagonal() = (dA.diagonal().array()==0).select(1,dA.diagonal());
+    A = dA.sparseView();
+    A.makeCompressed();
+  
     check_sparse_determinant(solver, A, dA);
   }
 }
@@ -350,13 +503,63 @@
   typedef typename Mat::Scalar Scalar;
   typedef Matrix<Scalar,Dynamic,Dynamic> DenseMatrix;
 
-  // generate the problem
-  Mat A;
-  DenseMatrix dA;
-  generate_sparse_square_problem(solver, A, dA, 30);
-  A.makeCompressed();
   for (int i = 0; i < g_repeat; i++) {
+    // generate the problem
+    Mat A;
+    DenseMatrix dA;
+    generate_sparse_square_problem(solver, A, dA, 30);
+    A.makeCompressed();
     check_sparse_abs_determinant(solver, A, dA);
   }
 }
 
+template<typename Solver, typename DenseMat>
+void generate_sparse_leastsquare_problem(Solver&, typename Solver::MatrixType& A, DenseMat& dA, int maxSize = 300, int options = ForceNonZeroDiag)
+{
+  typedef typename Solver::MatrixType Mat;
+  typedef typename Mat::Scalar Scalar;
+
+  int rows = internal::random<int>(1,maxSize);
+  int cols = internal::random<int>(1,rows);
+  double density = (std::max)(8./(rows*cols), 0.01);
+  
+  A.resize(rows,cols);
+  dA.resize(rows,cols);
+
+  initSparse<Scalar>(density, dA, A, options);
+}
+
+template<typename Solver> void check_sparse_leastsquare_solving(Solver& solver)
+{
+  typedef typename Solver::MatrixType Mat;
+  typedef typename Mat::Scalar Scalar;
+  typedef SparseMatrix<Scalar,ColMajor, typename Mat::StorageIndex> SpMat;
+  typedef Matrix<Scalar,Dynamic,Dynamic> DenseMatrix;
+  typedef Matrix<Scalar,Dynamic,1> DenseVector;
+
+  int rhsCols = internal::random<int>(1,16);
+
+  Mat A;
+  DenseMatrix dA;
+  for (int i = 0; i < g_repeat; i++) {
+    generate_sparse_leastsquare_problem(solver, A, dA);
+
+    A.makeCompressed();
+    DenseVector b = DenseVector::Random(A.rows());
+    DenseMatrix dB(A.rows(),rhsCols);
+    SpMat B(A.rows(),rhsCols);
+    double density = (std::max)(8./(A.rows()*rhsCols), 0.1);
+    initSparse<Scalar>(density, dB, B, ForceNonZeroDiag);
+    B.makeCompressed();
+    check_sparse_solving(solver, A, b,  dA, b);
+    check_sparse_solving(solver, A, dB, dA, dB);
+    check_sparse_solving(solver, A, B,  dA, dB);
+    
+    // check only once
+    if(i==0)
+    {
+      b = DenseVector::Zero(A.rows());
+      check_sparse_solving(solver, A, b, dA, b);
+    }
+  }
+}