diff --git a/doc/snippets/MatrixBase_isDiagonal.cpp b/doc/snippets/MatrixBase_isDiagonal.cpp
new file mode 100644
index 0000000..5b1d599
--- /dev/null
+++ b/doc/snippets/MatrixBase_isDiagonal.cpp
@@ -0,0 +1,6 @@
+Matrix3d m = 10000 * Matrix3d::Identity();
+m(0,2) = 1;
+cout << "Here's the matrix m:" << endl << m << endl;
+cout << "m.isDiagonal() returns: " << m.isDiagonal() << endl;
+cout << "m.isDiagonal(1e-3) returns: " << m.isDiagonal(1e-3) << endl;
+