namespace Eigen {

/** \page TopicPitfalls Common pitfalls

\section TopicPitfalls_template_keyword Compilation error with template methods

See this \link TopicTemplateKeyword page \endlink.

\section TopicPitfalls_auto_keyword C++11 and the auto keyword

In short: do not use the auto keywords with Eigen's expressions, unless you are 100% sure about what you are doing. In particular, do not use the auto keyword as a replacement for a Matrix<> type. Here is an example:

\code
MatrixXd A, B;
auto C = A*B;
for(...) { ... w = C * v;  ...}
\endcode

In this example, the type of C is not a MatrixXd but an abstract expression representing a matrix product and storing references to A and B. Therefore, the product of A*B will be carried out multiple times, once per iteration of the for loop. Moreover, if the coefficients of A or B change during the iteration, then C will evaluate to different values.

*/
}