private Mx leftContract(final Mx original) { final VecBasedMx contracted = new VecBasedMx(original.rows(), original.columns() - 1); for (int i = 0; i < contracted.rows(); i++) { for (int j = 0; j < contracted.columns(); j++) { contracted.set(i, j, original.get(i, j + 1)); } } return contracted; }