//
// dercent.h
//
// Copyright (C) 1996 Limit Point Systems, Inc.
//
// Author: Curtis Janssen <cljanss@limitpt.com>
// Maintainer: LPS
//
// This file is part of the SC Toolkit.
//
// The SC Toolkit is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// The SC Toolkit is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with the SC Toolkit; see the file COPYING.LIB.  If not, write to
// the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
//
// The U.S. Government is granted a limited license as per AL 91-7.
//

#ifdef __GNUC__
#pragma interface
#endif

#ifndef _chemistry_qc_basis_dercent_h
#define _chemistry_qc_basis_dercent_h

#include <chemistry/qc/basis/basis.h>

namespace sc {

/** DerivCenters keeps track the centers that
    derivatives are taken with respect to. */
class DerivCenters {
  private:
    int center_[4];
    int atom_[4];
    int ncenter_;
    int omitted_center_;
    int omitted_atom_;
  public:
    /// Construct a new, empty DerivCenters object.
    DerivCenters();

    /// @name Routines to Modify DerivCenters
    //@{
    /// Clear the list of centers.
    void clear();
    /** Add a center using a basis set and the shell number.
     * @param center The center number (between 0 and 3 inclusive).
     * @param bs     The basis set for this center.
     * @param shell  The shell number for this center.
     */
    void add_center(int center, const Ref<GaussianBasisSet> &bs, int shell);
    /** Add a center using the atom number.
     * @param center The center number (between 0 and 3 inclusive).
     * @param atom   The center within a GaussianBasisSet.
     */
    void add_center(int center, int atom);
    /** Add the omitted center using a basis set and the shell number.
     * @param center The center number (between 0 and 3 inclusive).
     * @param bs     The basis set for this center.
     * @param shell  The shell number for this center.
     */
    void add_omitted(int center, const Ref<GaussianBasisSet> &bs, int shell);
    /** Add the omitted center using the atom number.
     * @param center The center number (between 0 and 3 inclusive).
     * @param atom   The center within a GaussianBasisSet.
     */
    void add_omitted(int center, int atom);
    //@}

    /// @name Routines to Query DerivCenters
    //@{
    /// The number of centers for which derivatives have been computed.
    int n() const { return ncenter_; }
    /** @param i The computed center index (between 0 and n() - 1, inclusive).
     *  @return The center number (between 0 and 3, inclusive).
     */
    int center(int i) const { return center_[i]; }
    /** @param i The computed center index (between 0 and n() - 1, inclusive).
     *  @return The atom number.
     */
    int atom(int i) const { return atom_[i]; }
    /** @return 1 if there is an omitted center, otherwise 0.
     */
    int has_omitted_center() const { return omitted_center_ >= 0; }
    /** @return The center for which integrals where not computed.
     */
    int omitted_center() const { return omitted_center_; }
    /** @return The atom that is omitted from the integral buffer.
     */
    int omitted_atom() const { return omitted_atom_; }
    //}@
};

}

#endif

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// mode: c++
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