fix warnings for doc-eigen-prerequisites
diff --git a/doc/snippets/MatrixBase_cwiseEqual.cpp b/doc/snippets/MatrixBase_cwiseEqual.cpp
index eb3656f..469af64 100644
--- a/doc/snippets/MatrixBase_cwiseEqual.cpp
+++ b/doc/snippets/MatrixBase_cwiseEqual.cpp
@@ -3,5 +3,5 @@
1, 1;
cout << "Comparing m with identity matrix:" << endl;
cout << m.cwiseEqual(MatrixXi::Identity(2,2)) << endl;
-int count = m.cwiseEqual(MatrixXi::Identity(2,2)).count();
+Index count = m.cwiseEqual(MatrixXi::Identity(2,2)).count();
cout << "Number of coefficients that are equal: " << count << endl;