[eigen] An insistent plea for an input operator

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I know, I've asked for this feature several month, ago,
but I'm obstinate to ask for it again and again.

Background: I'm teaching C++ for beginners (mathematicians) and
there should be an easy input operator for matrices and vectors.

Currently, I have to patch Eigen (2 or 3) by adding

namespace Eigen {
template<typename Derived>
std::istream & operator >>(std::istream & Inp, MatrixBase<Derived> & m) 
  for (int i = 0; i < m.rows(); ++i)
    for (int j = 0; j < m.cols(); j++)
      Inp >> m(i,j);
  return Inp;


to make the following simple program run

int main() {
Eigen::MatrixXi A(2,3);
  std::cerr << "intput 2x3 matrix:\n";
  std::cin >> A;
  std::cout << "I've got:\n" << A << std::endl;

I've never understood the objections against adding this.
Pardon for being such obstinate,

My problem is, that students download Eigen themselves and forget about
adding these few lines.

Helmut Jarausch

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

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