[eigen] type of comma initializer ?

[Helmut Jarausch <jarausch@xxxxxxxxxxxxxxxxxxx>]

Hi,

I'd like to put the initialization of a Matrix like

Matrix<int,3,1> A;

A << 1,2,3;

into a function. I'd like to pass the object "1,2,3" as a parameter.
What's the type of this expression. Or, what to fill in for 
<UNKNOWN_TYPE> below?

void Mat_init(Matrix<int,3,1>& X, <UNKNOWN_TYPE>&  Ini) {
  X << Ini;
}

Many thanks for a hint,
Helmut.