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A collection of classes shared by broadleaf profile, cms, admin, and core.

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/*
 * #%L
 * BroadleafCommerce Common Libraries
 * %%
 * Copyright (C) 2009 - 2013 Broadleaf Commerce
 * %%
 * Licensed 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.
 * #L%
 */
package org.broadleafcommerce.common.util;

public class StatCalc {

    private int count;   // Number of numbers that have been entered.
    private double sum;  // The sum of all the items that have been entered.
    private double squareSum;  // The sum of the squares of all the items.
    private double max = Double.NEGATIVE_INFINITY;  // Largest item seen.
    private double min = Double.POSITIVE_INFINITY;  // Smallest item seen.

    public void enter(double num) {
        // Add the number to the dataset.
        count++;
        sum += num;
        squareSum += num*num;
        if (num > max)
            max = num;
        if (num < min)
            min = num;
    }

    public int getCount() {
        // Return number of items that have been entered.
        return count;
    }

    public double getSum() {
        // Return the sum of all the items that have been entered.
        return sum;
    }

    public double getMean() {
        // Return average of all the items that have been entered.
        // Value is Double.NaN if count == 0.
        return sum / count;
    }

    public double getStandardDeviation() {
        // Return standard deviation of all the items that have been entered.
        // Value will be Double.NaN if count == 0.
        double mean = getMean();
        return Math.sqrt( squareSum/count - mean*mean );
    }

    public double getMin() {
        // Return the smallest item that has been entered.
        // Value will be infinity if no items have been entered.
        return min;
    }

    public double getMax() {
        // Return the largest item that has been entered.
        // Value will be -infinity if no items have been entered.
        return max;
    }

}