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camvox/Interval.h

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/* Interval.h - Interval arrithmatic class.
 * Copyright (C) 2008  Take Vos
 *
 * 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 GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef INTERVAL_H
#define INTERVAL_H

#include <camvox/GMath.h>

namespace camvox {

/* This interval class likes the number to be rounded down.
 */
template <class T>
class TInterval {
public:
        T       low, high;

        TInterval(T _low, T _high) {
                low = _low;
                high = _high;
        }

        TInterval(T value) {
                low = high = value;
        }

        ~TInterval() {}

        TInterval operator+(const TInterval &other) const {
                T low = this->low + other.low;
                T high = (-this->high) + (-other.high);

                return TInterval(low, -high);
        }

        TInterval operator-(const TInterval &other) const {
                T low = this->low + (-other.high);
                T high = (-this->high) + other.low;

                return TInterval(low, -high);
        }

        TInterval operator*(const TInterval &other) const {
                T low = gmin(
                                gmin(this->low * other.low, this->low * other.high),
                                gmin(this->high * other.low, this->high * other.high)
                );
                T high = gmax(
                                gmax(this->low * other.low, this->low * other.high),
                                gmax(this->high * other.low, this->high * other.high)
                );

                return TInterval(low, high);
        }

        TInterval operator/(const TInterval &other) const {
                T low = gmin(
                                gmin(this->low / other.low, this->low / other.high),
                                gmin(this->high / other.low, this->high / other.high)
                );
                T high = gmax(
                                gmax(this->low / other.low, this->low / other.high),
                                gmax(this->high / other.low, this->high / other.high)
                );

                return TInterval(low, high);
        }

        TInterval abs(void) const {
                T low = gmax(gmax(this->low, -this->high), 0.0);
                T high = gmax(-this->low, this->high);
                return TInterval(low, high);
        }

        TInterval square(void) const {
                TInterval tmp = this->abs();

                T low = gmin(tmp.low * tmp.low, tmp.high * tmp.low);
                T high = gmax(tmp.high * tmp.high, tmp.low * tmp.high);

                return TInterval(low, high);
        }

        TInterval squareroot(void) const {
                TInterval tmp = this->abs();

                T low = sqrt(tmp.low);
                T high = sqrt(tmp.high);

                return TInterval(low, high);
        }
};

typedef TInterval<double>       Interval;

static inline Interval gsquare(Interval a) {
        return a.square();
}

}
#endif