Metrics.h

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// -*- lsst-c++ -*-

/* 
 * LSST Data Management System
 * Copyright 2008, 2009, 2010 LSST Corporation.
 * 
 * This product includes software developed by the
 * LSST Project (http://www.lsst.org/).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 * 
 * You should have received a copy of the LSST License Statement and 
 * the GNU General Public License along with this program.  If not, 
 * see <http://www.lsstcorp.org/LegalNotices/>.
 */
 
#ifndef LSST_AP_CLUSTER_DETAIL_METRICS_H
#define LSST_AP_CLUSTER_DETAIL_METRICS_H

#include <cmath>

#include "Eigen/Core"


namespace lsst { namespace ap { namespace cluster { namespace detail {

struct SquaredEuclidianDistanceOverSphere {
    double operator()(Eigen::Vector3d const & v1,
                      Eigen::Vector3d const & v2) const
    {
        return (v1 - v2).squaredNorm();
    }

    double operator()(double s, double t) const {
        return 2.0 * (1.0 - s * t - std::sqrt((1.0 - s * s) * (1.0 - t * t)));
    }
};

}}}} // lsst::ap::cluster::detail

#endif // LSST_AP_CLUSTER_DETAIL_METRICS_H