doc: Explain type of result for VectorwiseOp member functions.

Prompted by a question on the forum.

1 files changed, 3 insertions, 1 deletions

diff --git a/doc/snippets/PartialRedux_count.cpp b/doc/snippets/PartialRedux_count.cpp
index c7b3097e4..1c3b3a28f 100644
--- a/doc/snippets/PartialRedux_count.cpp
+++ b/doc/snippets/PartialRedux_count.cpp
@@ -1,3 +1,5 @@
 Matrix3d m = Matrix3d::Random();
 cout << "Here is the matrix m:" << endl << m << endl;
-cout << "Here is the count of elements larger or equal than 0.5 of each row:" << endl << (m.array() >= 0.5).rowwise().count() << endl;
+Matrix<ptrdiff_t, 3, 1> res = (m.array() >= 0.5).rowwise().count();
+cout << "Here is the count of elements larger or equal than 0.5 of each row:" << endl;
+cout << res << endl;