When running the following code:

  sgpp::base::DataMatrix mat(3, 1);
  mat(0, 0) = 0;
  mat(1, 0) = 1;
  mat(2, 0) = 2;
  mat.resizeToSubMatrix(1, 0, 2, 0);

the matrix should have the entries 1 and 2 left in it. However, the matrix has the entries <uninitialized> and 0. Therefore there must be an off-by-two error somewhere in that function.