add a sparse * dense_vector bench
diff --git a/bench/BenchSparseUtil.h b/bench/BenchSparseUtil.h
index 26a2f47..b823567 100644
--- a/bench/BenchSparseUtil.h
+++ b/bench/BenchSparseUtil.h
@@ -21,6 +21,7 @@
 
 typedef SCALAR Scalar;
 typedef Matrix<Scalar,Dynamic,Dynamic> DenseMatrix;
+typedef Matrix<Scalar,Dynamic,1> DenseVector;
 typedef SparseMatrix<Scalar> EigenSparseMatrix;
 
 void fillMatrix(float density, int rows, int cols,  EigenSparseMatrix& dst)
diff --git a/bench/sparse_dense_product.cpp b/bench/sparse_dense_product.cpp
new file mode 100644
index 0000000..3caf859
--- /dev/null
+++ b/bench/sparse_dense_product.cpp
@@ -0,0 +1,198 @@
+
+//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 -DCSPARSE
+// -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(); }
+
+
+#ifdef CSPARSE
+cs* cs_sorted_multiply(const cs* a, const cs* b)
+{
+  cs* A = cs_transpose (a, 1) ;
+  cs* B = cs_transpose (b, 1) ;
+  cs* D = cs_multiply (B,A) ;   /* D = B'*A' */
+  cs_spfree (A) ;
+  cs_spfree (B) ;
+  cs_dropzeros (D) ;      /* drop zeros from D */
+  cs* C = cs_transpose (D, 1) ;   /* C = D', so that C is sorted */
+  cs_spfree (D) ;
+  return C;
+}
+#endif
+
+int main(int argc, char *argv[])
+{
+  int rows = SIZE;
+  int cols = SIZE;
+  float density = DENSITY;
+
+  EigenSparseMatrix sm1(rows,cols);
+  DenseVector v1(cols), v2(cols);
+  v1.setRandom();
+
+  BenchTimer timer;
+  for (float density = DENSITY; density>=MINDENSITY; density*=0.5)
+  {
+    fillMatrix(density, rows, cols, sm1);
+
+    // dense matrices
+    #ifdef DENSEMATRIX
+    {
+      std::cout << "Eigen Dense\t" << density*100 << "%\n";
+      DenseMatrix m1(rows,cols);
+      eiToDense(sm1, m1);
+
+      timer.reset();
+      timer.start();
+      for (int k=0; k<REPEAT; ++k)
+        v2 = m1 * v1;
+      timer.stop();
+      std::cout << "   a * v:\t" << timer.value() << endl;
+
+      timer.reset();
+      timer.start();
+      for (int k=0; k<REPEAT; ++k)
+        v2 = m1.transpose() * v1;
+      timer.stop();
+      std::cout << "   a' * v:\t" << timer.value() << endl;
+    }
+    #endif
+
+    // eigen sparse matrices
+    {
+      std::cout << "Eigen sparse\t" << sm1.nonZeros()/float(sm1.rows()*sm1.cols())*100 << "%\n";
+
+//       timer.reset();
+//       timer.start();
+      BENCH(for (int k=0; k<REPEAT; ++k) v2 = sm1 * v1;)
+//       timer.stop();
+      std::cout << "   a * v:\t" << timer.value() << endl;
+//       std::cout << sm3 << "\n";
+
+      timer.reset();
+      timer.start();
+//       std::cerr << "transpose...\n";
+//       EigenSparseMatrix sm4 = sm1.transpose();
+//       std::cout << sm4.nonZeros() << " == " << sm1.nonZeros() << "\n";
+//       exit(1);
+//       std::cerr << "transpose OK\n";
+//       std::cout << sm1 << "\n\n" << sm1.transpose() << "\n\n" << sm4.transpose() << "\n\n";
+      BENCH(for (int k=0; k<REPEAT; ++k) v2 = sm1.transpose() * v1;)
+//       timer.stop();
+      std::cout << "   a' * v:\t" << timer.value() << endl;
+    }
+
+    // CSparse
+    #ifdef CSPARSE
+    {
+      std::cout << "CSparse \t" << density*100 << "%\n";
+      cs *m1, *m2, *m3;
+      eiToCSparse(sm1, m1);
+      eiToCSparse(sm2, m2);
+
+      timer.reset();
+      timer.start();
+      for (int k=0; k<REPEAT; ++k)
+      {
+        m3 = cs_sorted_multiply(m1, m2);
+        if (!m3)
+        {
+          std::cerr << "cs_multiply failed\n";
+//           break;
+        }
+//         cs_print(m3, 0);
+        cs_spfree(m3);
+      }
+      timer.stop();
+      std::cout << "   a * b:\t" << timer.value() << endl;
+    }
+    #endif
+
+    // GMM++
+    #ifndef NOGMM
+    {
+      std::cout << "GMM++ sparse\t" << density*100 << "%\n";
+      //GmmDynSparse  gmmT3(rows,cols);
+      GmmSparse m1(rows,cols);
+      eiToGmm(sm1, m1);
+      
+      std::vector<Scalar> gmmV1(cols), gmmV2(cols);
+      Map<Matrix<Scalar,Dynamic,1> >(&gmmV1[0], cols) = v1;
+      Map<Matrix<Scalar,Dynamic,1> >(&gmmV2[0], cols) = v2;
+
+      timer.reset();
+      timer.start();
+      for (int k=0; k<REPEAT; ++k)
+        gmm::mult(m1, gmmV1, gmmV2);
+      timer.stop();
+      std::cout << "   a * v:\t" << timer.value() << endl;
+
+      timer.reset();
+      timer.start();
+      for (int k=0; k<REPEAT; ++k)
+        gmm::mult(gmm::transposed(m1), gmmV1, gmmV2);
+      timer.stop();
+      std::cout << "   a' * v:\t" << timer.value() << endl;
+    }
+    #endif
+
+    // MTL4
+    #ifndef NOMTL
+    {
+      std::cout << "MTL4\t" << density*100 << "%\n";
+      MtlSparse m1(rows,cols);
+      eiToMtl(sm1, m1);
+      mtl::dense_vector<Scalar> mtlV1(cols, 1.0);
+      mtl::dense_vector<Scalar> mtlV2(cols, 1.0);
+
+      timer.reset();
+      timer.start();
+      for (int k=0; k<REPEAT; ++k)
+        mtlV2 = m1 * mtlV1;
+      timer.stop();
+      std::cout << "   a * v:\t" << timer.value() << endl;
+
+      timer.reset();
+      timer.start();
+      for (int k=0; k<REPEAT; ++k)
+        mtlV2 = trans(m1) * mtlV1;
+      timer.stop();
+      std::cout << "   a' * v:\t" << timer.value() << endl;
+    }
+    #endif
+
+    std::cout << "\n\n";
+  }
+
+  return 0;
+}
+