// Copyright (c) 2008 Max-Planck-Institute Saarbruecken (Germany)
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v5.6.1/Polynomial/include/CGAL/Polynomial/hgdelta_update.h $
// $Id: hgdelta_update.h 0779373 2020-03-26T13:31:46+01:00 Sébastien Loriot
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s)     : Michael Hemmer
// ============================================================================

// TODO: The comments are all original EXACUS comments and aren't adapted. So
//         they may be wrong now.

#ifndef CGAL_POLYNOMIAL_HGDELTA_UPDATE_H
#define CGAL_POLYNOMIAL_HGDELTA_UPDATE_H

namespace CGAL {

// This subroutine has been retained here for use in both new files.
namespace internal {
    template <class NT> inline
    void hgdelta_update(NT& h, const NT& g, int delta) {
        typename Algebraic_structure_traits<NT>::Integral_division idiv;

        // compute h = h^(1-delta) * g^delta
        switch (delta) {
        case 0:
            // h = h;
            break;
        case 1:
            h = g;
            break;
        default:
            h = idiv(CGAL::ipower(g, delta), CGAL::ipower(h, delta-1));
            break;
        }
    }
} // namespace internal

} //namespace CGAL

#endif // CGAL_POLYNOMIAL_HGDELTA_UPDATE_H

