/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math3.stat.descriptive.rank;

import java.io.Serializable;

import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic;
import org.apache.commons.math3.util.MathUtils;

Returns the maximum of the available values.


The result is NaN iff all values are NaN
(i.e. NaN values have no impact on the value of the statistic).
If any of the values equals Double.POSITIVE_INFINITY,
the result is Double.POSITIVE_INFINITY.


Note that this implementation is not synchronized. If
multiple threads access an instance of this class concurrently, and at least
one of the threads invokes the increment() or
clear() method, it must be synchronized externally.
/**
 * Returns the maximum of the available values.
 * <p>
 * <ul>
 * <li>The result is <code>NaN</code> iff all values are <code>NaN</code>
 * (i.e. <code>NaN</code> values have no impact on the value of the statistic).</li>
 * <li>If any of the values equals <code>Double.POSITIVE_INFINITY</code>,
 * the result is <code>Double.POSITIVE_INFINITY.</code></li>
 * </ul></p>
* <p>
 * <strong>Note that this implementation is not synchronized.</strong> If
 * multiple threads access an instance of this class concurrently, and at least
 * one of the threads invokes the <code>increment()</code> or
 * <code>clear()</code> method, it must be synchronized externally.</p>
 *
 */
public class Max extends AbstractStorelessUnivariateStatistic implements Serializable {

    
Serializable version identifier /** Serializable version identifier */
    private static final long serialVersionUID = -5593383832225844641L;

    
Number of values that have been added /** Number of values that have been added */
    private long n;

    
Current value of the statistic /** Current value of the statistic */
    private double value;

    
Create a Max instance
/**
     * Create a Max instance
     */
    public Max() {
        n = 0;
        value = Double.NaN;
    }

    
Copy constructor, creates a new Max identical to the original 
Params:
original – the Max instance to copy
Throws:
NullArgumentException – if original is null/**
     * Copy constructor, creates a new {@code Max} identical
     * to the {@code original}
     *
     * @param original the {@code Max} instance to copy
     * @throws NullArgumentException if original is null
     */
    public Max(Max original) throws NullArgumentException {
        copy(original, this);
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void increment(final double d) {
        if (d > value || Double.isNaN(value)) {
            value = d;
        }
        n++;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public void clear() {
        value = Double.NaN;
        n = 0;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public double getResult() {
        return value;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public long getN() {
        return n;
    }

    
Returns the maximum of the entries in the specified portion of
the input array, or Double.NaN if the designated subarray
is empty.

Throws MathIllegalArgumentException if the array is null or
the array index parameters are not valid.


The result is NaN iff all values are NaN
(i.e. NaN values have no impact on the value of the statistic).
If any of the values equals Double.POSITIVE_INFINITY,
the result is Double.POSITIVE_INFINITY.

Params:
values – the input array
begin – index of the first array element to include
length – the number of elements to include
Throws:
MathIllegalArgumentException – if the array is null or the array index
 parameters are not valid
Returns:
the maximum of the values or Double.NaN if length = 0/**
     * Returns the maximum of the entries in the specified portion of
     * the input array, or <code>Double.NaN</code> if the designated subarray
     * is empty.
     * <p>
     * Throws <code>MathIllegalArgumentException</code> if the array is null or
     * the array index parameters are not valid.</p>
     * <p>
     * <ul>
     * <li>The result is <code>NaN</code> iff all values are <code>NaN</code>
     * (i.e. <code>NaN</code> values have no impact on the value of the statistic).</li>
     * <li>If any of the values equals <code>Double.POSITIVE_INFINITY</code>,
     * the result is <code>Double.POSITIVE_INFINITY.</code></li>
     * </ul></p>
     *
     * @param values the input array
     * @param begin index of the first array element to include
     * @param length the number of elements to include
     * @return the maximum of the values or Double.NaN if length = 0
     * @throws MathIllegalArgumentException if the array is null or the array index
     *  parameters are not valid
     */
    @Override
    public double evaluate(final double[] values, final int begin, final int length)
    throws MathIllegalArgumentException {
        double max = Double.NaN;
        if (test(values, begin, length)) {
            max = values[begin];
            for (int i = begin; i < begin + length; i++) {
                if (!Double.isNaN(values[i])) {
                    max = (max > values[i]) ? max : values[i];
                }
            }
        }
        return max;
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    @Override
    public Max copy() {
        Max result = new Max();
        // No try-catch or advertised exception because args are non-null
        copy(this, result);
        return result;
    }

    
Copies source to dest.
Neither source nor dest can be null.
Params:
source – Max to copy
dest – Max to copy to
Throws:
NullArgumentException – if either source or dest is null/**
     * Copies source to dest.
     * <p>Neither source nor dest can be null.</p>
     *
     * @param source Max to copy
     * @param dest Max to copy to
     * @throws NullArgumentException if either source or dest is null
     */
    public static void copy(Max source, Max dest)
        throws NullArgumentException {
        MathUtils.checkNotNull(source);
        MathUtils.checkNotNull(dest);
        dest.setData(source.getDataRef());
        dest.n = source.n;
        dest.value = source.value;
    }
}