Update eigenvalues() and operatorNorm() methods in MatrixBase.
* use SelfAdjointView instead of Eigen2's SelfAdjoint flag.
* add tests and documentation.
* allow eigenvalues() for non-selfadjoint matrices.
* they no longer depend only on SelfAdjointEigenSolver, so move them to
a separate file
diff --git a/doc/snippets/MatrixBase_eigenvalues.cpp b/doc/snippets/MatrixBase_eigenvalues.cpp
new file mode 100644
index 0000000..039f887
--- /dev/null
+++ b/doc/snippets/MatrixBase_eigenvalues.cpp
@@ -0,0 +1,3 @@
+MatrixXd ones = MatrixXd::Ones(3,3);
+VectorXcd eivals = ones.eigenvalues();
+cout << "The eigenvalues of the 3x3 matrix of ones are:" << endl << eivals << endl;
diff --git a/doc/snippets/MatrixBase_operatorNorm.cpp b/doc/snippets/MatrixBase_operatorNorm.cpp
new file mode 100644
index 0000000..355246f
--- /dev/null
+++ b/doc/snippets/MatrixBase_operatorNorm.cpp
@@ -0,0 +1,3 @@
+MatrixXd ones = MatrixXd::Ones(3,3);
+cout << "The operator norm of the 3x3 matrix of ones is "
+ << ones.operatorNorm() << endl;
diff --git a/doc/snippets/SelfAdjointView_eigenvalues.cpp b/doc/snippets/SelfAdjointView_eigenvalues.cpp
new file mode 100644
index 0000000..be19867
--- /dev/null
+++ b/doc/snippets/SelfAdjointView_eigenvalues.cpp
@@ -0,0 +1,3 @@
+MatrixXd ones = MatrixXd::Ones(3,3);
+VectorXd eivals = ones.selfadjointView<Lower>().eigenvalues();
+cout << "The eigenvalues of the 3x3 matrix of ones are:" << endl << eivals << endl;
diff --git a/doc/snippets/SelfAdjointView_operatorNorm.cpp b/doc/snippets/SelfAdjointView_operatorNorm.cpp
new file mode 100644
index 0000000..f380f55
--- /dev/null
+++ b/doc/snippets/SelfAdjointView_operatorNorm.cpp
@@ -0,0 +1,3 @@
+MatrixXd ones = MatrixXd::Ones(3,3);
+cout << "The operator norm of the 3x3 matrix of ones is "
+ << ones.selfadjointView<Lower>().operatorNorm() << endl;