diff --git a/bench/sparse_trisolver.cpp b/bench/sparse_trisolver.cpp
new file mode 100644
index 0000000..13f4f0a
--- /dev/null
+++ b/bench/sparse_trisolver.cpp
@@ -0,0 +1,220 @@
+
+//g++ -O3 -g0 -DNDEBUG  sparse_product.cpp -I.. -I/home/gael/Coding/LinearAlgebra/mtl4/ -DDENSITY=0.005 -DSIZE=10000 && ./a.out
+//g++ -O3 -g0 -DNDEBUG  sparse_product.cpp -I.. -I/home/gael/Coding/LinearAlgebra/mtl4/ -DDENSITY=0.05 -DSIZE=2000 && ./a.out
+// -DNOGMM -DNOMTL
+// -I /home/gael/Coding/LinearAlgebra/CSparse/Include/ /home/gael/Coding/LinearAlgebra/CSparse/Lib/libcsparse.a
+
+#ifndef SIZE
+#define SIZE 10000
+#endif
+
+#ifndef DENSITY
+#define DENSITY 0.01
+#endif
+
+#ifndef REPEAT
+#define REPEAT 1
+#endif
+
+#include "BenchSparseUtil.h"
+
+#ifndef MINDENSITY
+#define MINDENSITY 0.0004
+#endif
+
+#ifndef NBTRIES
+#define NBTRIES 10
+#endif
+
+#define BENCH(X) \
+  timer.reset(); \
+  for (int _j=0; _j<NBTRIES; ++_j) { \
+    timer.start(); \
+    for (int _k=0; _k<REPEAT; ++_k) { \
+        X  \
+  } timer.stop(); }
+
+typedef SparseMatrix<Scalar,UpperTriangular> EigenSparseTriMatrix;
+typedef SparseMatrix<Scalar,RowMajorBit|UpperTriangular> EigenSparseTriMatrixRow;
+
+void fillMatrix(float density, int rows, int cols,  EigenSparseTriMatrix& dst)
+{
+  dst.startFill(rows*cols*density);
+  for(int j = 0; j < cols; j++)
+  {
+    for(int i = 0; i < j; i++)
+    {
+      Scalar v = (internal::random<float>(0,1) < density) ? internal::random<Scalar>() : 0;
+      if (v!=0)
+        dst.fill(i,j) = v;
+    }
+    dst.fill(j,j) = internal::random<Scalar>();
+  }
+  dst.endFill();
+}
+
+int main(int argc, char *argv[])
+{
+  int rows = SIZE;
+  int cols = SIZE;
+  float density = DENSITY;
+  BenchTimer timer;
+  #if 1
+  EigenSparseTriMatrix sm1(rows,cols);
+  typedef Matrix<Scalar,Dynamic,1> DenseVector;
+  DenseVector b = DenseVector::Random(cols);
+  DenseVector x = DenseVector::Random(cols);
+
+  bool densedone = false;
+
+  for (float density = DENSITY; density>=MINDENSITY; density*=0.5)
+  {
+    EigenSparseTriMatrix sm1(rows, cols);
+    fillMatrix(density, rows, cols, sm1);
+
+    // dense matrices
+    #ifdef DENSEMATRIX
+    if (!densedone)
+    {
+      densedone = true;
+      std::cout << "Eigen Dense\t" << density*100 << "%\n";
+      DenseMatrix m1(rows,cols);
+      Matrix<Scalar,Dynamic,Dynamic,Dynamic,Dynamic,RowMajorBit> m2(rows,cols);
+      eiToDense(sm1, m1);
+      m2 = m1;
+
+      BENCH(x = m1.marked<UpperTriangular>().solveTriangular(b);)
+      std::cout << "   colmajor^-1 * b:\t" << timer.value() << endl;
+//       std::cerr << x.transpose() << "\n";
+
+      BENCH(x = m2.marked<UpperTriangular>().solveTriangular(b);)
+      std::cout << "   rowmajor^-1 * b:\t" << timer.value() << endl;
+//       std::cerr << x.transpose() << "\n";
+    }
+    #endif
+
+    // eigen sparse matrices
+    {
+      std::cout << "Eigen sparse\t" << density*100 << "%\n";
+      EigenSparseTriMatrixRow sm2 = sm1;
+
+      BENCH(x = sm1.solveTriangular(b);)
+      std::cout << "   colmajor^-1 * b:\t" << timer.value() << endl;
+//       std::cerr << x.transpose() << "\n";
+
+      BENCH(x = sm2.solveTriangular(b);)
+      std::cout << "   rowmajor^-1 * b:\t" << timer.value() << endl;
+//       std::cerr << x.transpose() << "\n";
+
+//       x = b;
+//       BENCH(sm1.inverseProductInPlace(x);)
+//       std::cout << "   colmajor^-1 * b:\t" << timer.value() << " (inplace)" << endl;
+//       std::cerr << x.transpose() << "\n";
+//
+//       x = b;
+//       BENCH(sm2.inverseProductInPlace(x);)
+//       std::cout << "   rowmajor^-1 * b:\t" << timer.value() << " (inplace)" << endl;
+//       std::cerr << x.transpose() << "\n";
+    }
+
+
+
+    // CSparse
+    #ifdef CSPARSE
+    {
+      std::cout << "CSparse \t" << density*100 << "%\n";
+      cs *m1;
+      eiToCSparse(sm1, m1);
+
+      BENCH(x = b; if (!cs_lsolve (m1, x.data())){std::cerr << "cs_lsolve failed\n"; break;}; )
+      std::cout << "   colmajor^-1 * b:\t" << timer.value() << endl;
+    }
+    #endif
+
+    // GMM++
+    #ifndef NOGMM
+    {
+      std::cout << "GMM++ sparse\t" << density*100 << "%\n";
+      GmmSparse m1(rows,cols);
+      gmm::csr_matrix<Scalar> m2;
+      eiToGmm(sm1, m1);
+      gmm::copy(m1,m2);
+      std::vector<Scalar> gmmX(cols), gmmB(cols);
+      Map<Matrix<Scalar,Dynamic,1> >(&gmmX[0], cols) = x;
+      Map<Matrix<Scalar,Dynamic,1> >(&gmmB[0], cols) = b;
+
+      gmmX = gmmB;
+      BENCH(gmm::upper_tri_solve(m1, gmmX, false);)
+      std::cout << "   colmajor^-1 * b:\t" << timer.value() << endl;
+//       std::cerr << Map<Matrix<Scalar,Dynamic,1> >(&gmmX[0], cols).transpose() << "\n";
+
+      gmmX = gmmB;
+      BENCH(gmm::upper_tri_solve(m2, gmmX, false);)
+      timer.stop();
+      std::cout << "   rowmajor^-1 * b:\t" << timer.value() << endl;
+//       std::cerr << Map<Matrix<Scalar,Dynamic,1> >(&gmmX[0], cols).transpose() << "\n";
+    }
+    #endif
+
+    // MTL4
+    #ifndef NOMTL
+    {
+      std::cout << "MTL4\t" << density*100 << "%\n";
+      MtlSparse m1(rows,cols);
+      MtlSparseRowMajor m2(rows,cols);
+      eiToMtl(sm1, m1);
+      m2 = m1;
+      mtl::dense_vector<Scalar> x(rows, 1.0);
+      mtl::dense_vector<Scalar> b(rows, 1.0);
+
+      BENCH(x = mtl::upper_trisolve(m1,b);)
+      std::cout << "   colmajor^-1 * b:\t" << timer.value() << endl;
+//       std::cerr << x << "\n";
+
+      BENCH(x = mtl::upper_trisolve(m2,b);)
+      std::cout << "   rowmajor^-1 * b:\t" << timer.value() << endl;
+//       std::cerr << x << "\n";
+    }
+    #endif
+
+
+    std::cout << "\n\n";
+  }
+  #endif
+
+  #if 0
+    // bench small matrices (in-place versus return bye value)
+    {
+      timer.reset();
+      for (int _j=0; _j<10; ++_j) {
+        Matrix4f m = Matrix4f::Random();
+        Vector4f b = Vector4f::Random();
+        Vector4f x = Vector4f::Random();
+        timer.start();
+        for (int _k=0; _k<1000000; ++_k) {
+          b = m.inverseProduct(b);
+        }
+        timer.stop();
+      }
+      std::cout << "4x4 :\t" << timer.value() << endl;
+    }
+
+    {
+      timer.reset();
+      for (int _j=0; _j<10; ++_j) {
+        Matrix4f m = Matrix4f::Random();
+        Vector4f b = Vector4f::Random();
+        Vector4f x = Vector4f::Random();
+        timer.start();
+        for (int _k=0; _k<1000000; ++_k) {
+          m.inverseProductInPlace(x);
+        }
+        timer.stop();
+      }
+      std::cout << "4x4 IP :\t" << timer.value() << endl;
+    }
+  #endif
+
+  return 0;
+}
+