Squashed 'third_party/eigen/' content from commit 61d72f6

Change-Id: Iccc90fa0b55ab44037f018046d2fcffd90d9d025
git-subtree-dir: third_party/eigen
git-subtree-split: 61d72f6383cfa842868c53e30e087b0258177257
diff --git a/doc/snippets/MatrixBase_cwiseProduct.cpp b/doc/snippets/MatrixBase_cwiseProduct.cpp
new file mode 100644
index 0000000..1db3a11
--- /dev/null
+++ b/doc/snippets/MatrixBase_cwiseProduct.cpp
@@ -0,0 +1,4 @@
+Matrix3i a = Matrix3i::Random(), b = Matrix3i::Random();
+Matrix3i c = a.cwiseProduct(b);
+cout << "a:\n" << a << "\nb:\n" << b << "\nc:\n" << c << endl;
+