Extend documentation and add examples for EigenSolver class.
diff --git a/doc/snippets/EigenSolver_eigenvalues.cpp b/doc/snippets/EigenSolver_eigenvalues.cpp
new file mode 100644
index 0000000..8d83ea9
--- /dev/null
+++ b/doc/snippets/EigenSolver_eigenvalues.cpp
@@ -0,0 +1,4 @@
+MatrixXd ones = MatrixXd::Ones(3,3);
+EigenSolver<MatrixXd> es(ones);
+cout << "The eigenvalues of the 3x3 matrix of ones are:" 
+     << endl << es.eigenvalues() << endl;