package de.lmu.ifi.dbs.elki.math.statistics;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2012
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import gnu.trove.map.TDoubleDoubleMap;
import gnu.trove.map.TIntObjectMap;
import gnu.trove.map.hash.TDoubleDoubleHashMap;
import gnu.trove.map.hash.TIntObjectHashMap;
/**
* Tabelarizes the values for student distribution.
*
* @author Elke Achtert
*/
public class StudentDistribution {
/**
* Available alpha values.
*/
public static double _6000 = 0.6;
/**
* Available alpha values.
*/
public static double _8000 = 0.8;
/**
* Available alpha values.
*/
public static double _9000 = 0.9;
/**
* Available alpha values.
*/
public static double _9500 = 0.95;
/**
* Available alpha values.
*/
public static double _9750 = 0.975;
/**
* Available alpha values.
*/
public static double _9900 = 0.99;
/**
* Available alpha values.
*/
public static double _9950 = 0.995;
/**
* Available alpha values.
*/
public static double _9990 = 0.999;
/**
* Available alpha values.
*/
public static double _9995 = 0.9995;
/**
* Available alpha values.
*/
public static double _4000 = 0.4;
/**
* Available alpha values.
*/
public static double _2000 = 0.2;
/**
* Available alpha values.
*/
public static double _1000 = 0.1;
/**
* Available alpha values.
*/
public static double _0500 = 0.05;
/**
* Available alpha values.
*/
public static double _0250 = 0.025;
/**
* Available alpha values.
*/
public static double _0100 = 0.01;
/**
* Available alpha values.
*/
public static double _0050 = 0.005;
/**
* Available alpha values.
*/
public static double _0010 = 0.001;
/**
* Available alpha values.
*/
public static double _0005 = 0.005;
/**
* Holds the t-values.
*/
private static TIntObjectMap<TDoubleDoubleMap> tValues = new TIntObjectHashMap<TDoubleDoubleMap>();
static {
put(31, new double[] { 0.2533, 0.8416, 1.2816, 1.6449, 1.96, 2.3263, 2.5758, 3.0903, 3.2906 });
}
/**
* Returns the t-value for the given alpha-value and degree of freedom.
*
* @param alpha the alpha value
* @param n the degree of freedom
* @return the t-value for the given alpha-value and degree of freedom
*/
public static double tValue(double alpha, int n) {
if(n > 30) {
n = 31;
}
TDoubleDoubleMap map = tValues.get(n);
if(map == null) {
throw new IllegalArgumentException("t-values for n=" + n + " not yet tabularized!");
}
Double value = map.get(alpha);
if(value == null) {
throw new IllegalArgumentException("t-values for alpha=" + alpha + " not tabularized!");
}
return value;
}
/**
* Stores the specified t-values for the given degree of freedom.
*
* @param n the degree of freedom
* @param values the t-values
*/
private static void put(int n, double[] values) {
TDoubleDoubleMap map = new TDoubleDoubleHashMap();
map.put(_6000, values[0]);
map.put(_8000, values[1]);
map.put(_9000, values[2]);
map.put(_9500, values[3]);
map.put(_9750, values[4]);
map.put(_9900, values[5]);
map.put(_9950, values[6]);
map.put(_9990, values[7]);
map.put(_9995, values[8]);
map.put(_4000, -values[0]);
map.put(_2000, -values[1]);
map.put(_1000, -values[2]);
map.put(_0500, -values[3]);
map.put(_0250, -values[4]);
map.put(_0100, -values[5]);
map.put(_0050, -values[6]);
map.put(_0010, -values[7]);
map.put(_0005, -values[8]);
tValues.put(n, map);
}
}