message: remove a unnecessary apply and just set r2 to r
diff: @@ -142,8 +142,7 @@ void Bicg<ValueType, IndexType>::apply_impl(const LinOp *b, LinOp *x) const
  system_matrix_->apply(neg_one_op.get(), dense_x, one_op.get(), r.get());
  // r = r - Ax = -1.0 * A*dense_x + 1.0*r
  - // TODO set r2 = r so there has to be only one apply
  - system_matrix_->apply(neg_one_op.get(), dense_x, one_op.get(), r2.get());
  + r2->copy_from(r.get());
  // r2 = r
  auto stop_criterion = stop_criterion_factory_->generate(
  