[eigen] eigen3 replacement of start/segment/end

[Helmut Jarausch <jarausch@xxxxxxxxxxxxxxxxxxx>]

Hi

I have on old eigen2 function working with dense matrices

template<typename Derived>

void process(MatrixBase<Derived>& DATA) {
  Vector2d G;
  G << 1.0, 2.0;
  
  DATA.template start<2>()+= G;    // fails in Eigen3
  DATA.template segment<2>(0)+= G;
  
}

How can this be upgraded to Eigen3.
Many thanks for a hint,
Helmut.

-- 
Helmut Jarausch

Lehrstuhl fuer Numerische Mathematik
RWTH - Aachen University
D 52056 Aachen, Germany