r.base.distributions.UniformDistribution.java Source code

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Here is the source code for r.base.distributions.UniformDistribution.java

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/*
 * R : A Computer Language for Statistical Data Analysis
 * Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 * Copyright (C) 1997--2008  The R Development Core Team
 * Copyright (C) 2003, 2004  The R Foundation
 * Copyright (C) 2010 bedatadriven
 *
 * 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/>.
 */

package r.base.distributions;

import org.apache.commons.math.distribution.ContinuousDistribution;

/**
 * The uniform probability distribution.
 */
public class UniformDistribution implements ContinuousDistribution {
    private final double min;
    private final double max;
    private final double range;

    public UniformDistribution(double min, double max) {
        this.min = min;
        this.max = max;
        this.range = max - min;
    }

    @Override
    public double cumulativeProbability(double x) {
        if (x < min || x > max) {
            return 0;
        }
        return (x - min) / range;
    }

    public double density(double x) {
        if (x < min || x > max) {
            return 0;
        } else {
            return 1.0 / range;
        }
    }

    @Override
    public double inverseCumulativeProbability(double p) {
        return min + (p * range);
    }

    @Override
    public double cumulativeProbability(double x0, double x1) {
        if (x0 < min) {
            x0 = min;
        }
        if (x0 > max) {
            x0 = max;
        }
        if (x1 < min) {
            x1 = min;
        }
        if (x1 > max) {
            x1 = max;
        }
        return (x1 - x0) / range;
    }
}