[eigen] How to make optional template parameters in C++ ?

[<vincent.lejeune@xxxxxxxxxx>]

Hi,



I'm trying to make my own matrix type, which derivate from the 



Matrix< _Scalar,  _Rows,  _Cols,  _Options,  _MaxRows,  _MaxCols>



class. However, I don't know how to make the last 3 template parameters 

optionals for my own type, as it is done with the Matrix type.



I'd like to know what's the trick used to get optional templates

parameters to 

use it for my own matrix please.



Regards and Thanks,

Vincent