Squashed 'third_party/eigen/' changes from 61d72f6..cf794d3


Change-Id: I9b814151b01f49af6337a8605d0c42a3a1ed4c72
git-subtree-dir: third_party/eigen
git-subtree-split: cf794d3b741a6278df169e58461f8529f43bce5d
diff --git a/doc/snippets/Cwise_boolean_xor.cpp b/doc/snippets/Cwise_boolean_xor.cpp
new file mode 100644
index 0000000..fafbec8
--- /dev/null
+++ b/doc/snippets/Cwise_boolean_xor.cpp
@@ -0,0 +1,2 @@
+Array3d v(-1,2,1), w(-3,2,3);
+cout << ((v<w) ^ (v<0)) << endl;