diff()

Matrix * Matrix::diff	(	const Matrix *	m,
		int	use_coef ) const

Definition at line 805 of file matrix.cpp.

{
  const PolynomialRing *P = get_ring()->cast_to_PolynomialRing();
  if (P == nullptr)
    {
      ERROR("expected a polynomial ring");
      return nullptr;
    }
  if (P != m->get_ring())
    {
      ERROR("matrix diff: different base rings");
      return nullptr;
    }
  FreeModule *F1 = rows()->transpose();
  const FreeModule *F = F1->tensor(m->rows());
  FreeModule *G1 = cols()->transpose();
  const FreeModule *G = G1->tensor(m->cols());
 
  auto D = P->degree_monoid();
  monomial deg = D->make_one();
  D->divide(m->degree_shift(), degree_shift(), deg);
  freemem(F1);
  freemem(G1);
 
  MatrixConstructor mat(F, G, deg);
  D->remove(deg);
  int i, j, next = 0;
  for (i = 0; i < n_cols(); i++)
    for (j = 0; j < m->n_cols(); j++)
      mat.set_column(
          next++,
          P->vec_diff(elem(i), m->rows()->rank(), m->elem(j), use_coef));
  return mat.to_matrix();
}

References cols(), Ring::degree_monoid(), degree_shift(), diff(), elem(), ERROR, freemem(), FreeModule, G, get_ring(), Matrix(), MatrixConstructor, monomial, n_cols(), FreeModule::rank(), rows(), MatrixConstructor::set_column(), FreeModule::tensor(), MatrixConstructor::to_matrix(), and Ring::vec_diff().

Referenced by diff(), IM2_Matrix_contract(), and IM2_Matrix_diff().