diff --git a/src/extra/use_eigen_ex.cpp b/src/extra/use_eigen_ex.cpp
index 0ad6a97..032bfd2 100644
--- a/src/extra/use_eigen_ex.cpp
+++ b/src/extra/use_eigen_ex.cpp
@@ -48,5 +48,18 @@ int main(int argc, char const *argv[])
     _1d_array c;
     VectorXType2array(b, c);
     c.show();
+
+    _2d_matrix m(5, 6);
+    m.random_float(1, 2, RdUniform);
+    m.show();
+
+    Eigen::MatrixXd mat;
+    matrix2EigenMatrix(m, mat);
+    std::cout << mat << "\n";
+    std::cout << mat.transpose() << "\n";
+
+    _2d_matrix m2;
+    EigenMatrix2matrix(mat, m2);
+    m2.show();
     return 0;
 }