stats.distributions.Normal Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of java-timeseries Show documentation
Time Series Analysis in Java
The newest version!
/*
 * Copyright (c) 2016 Jacob Rachiele
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
 * and associated documentation files (the "Software"), to deal in the Software without restriction
 * including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense
 * and/or sell copies of the Software, and to permit persons to whom the Software is furnished to
 * do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Contributors:
 *
 * Jacob Rachiele
 */
package stats.distributions;

import lombok.ToString;
import smile.stat.distribution.GaussianDistribution;

/**
 * A Normal, or Gaussian, probability distribution.
 */
@ToString
public final class Normal implements Distribution {

    private final smile.stat.distribution.Distribution dist;
    private final double mean;
    private final double stdev;

    /**
     * Create a new Normal distribution with the given mean and standard deviation.
     *
     * @param mean the mean of the distribution.
     * @param stdev the standard deviation of the distribution.
     */
    public Normal(final double mean, final double stdev) {
        this.dist = new GaussianDistribution(mean, stdev);
        this.mean = mean;
        this.stdev = stdev;
    }

    /**
     * Create a new standard normal distribution with mean 0 and standard deviation 1.
     */
    public Normal() {
        this(0, 1);
    }

    @Override
    public final double rand() {
        return this.dist.rand();
    }

    @Override
    public final double quantile(final double prob) {
        return this.dist.quantile(prob);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Normal normal = (Normal) o;

        if (Double.compare(normal.mean, mean) != 0) return false;
        if (Double.compare(normal.stdev, stdev) != 0) return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result;
        long temp;
        temp = Double.doubleToLongBits(mean);
        result = (int) (temp ^ (temp >>> 32));
        temp = Double.doubleToLongBits(stdev);
        result = 31 * result + (int) (temp ^ (temp >>> 32));
        return result;
    }
}