[eigen] Keyword template

[Cedric Doucet <cedric.doucet@xxxxxxxx>]

Hello,

I had to use a keyword "template" to access some data:

Eigen::SparseMatrix<T> A;
A.template triangularView<Eigen::Upper>();

However, I don't understand how it works.
Could you explain me what it means and why it is necessary to use this keyword?

Thank you very much.

Cédric