diff options
Diffstat (limited to 'src/de/lmu/ifi/dbs/elki/math/statistics/StudentDistribution.java')
| -rw-r--r-- | src/de/lmu/ifi/dbs/elki/math/statistics/StudentDistribution.java | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/math/statistics/StudentDistribution.java b/src/de/lmu/ifi/dbs/elki/math/statistics/StudentDistribution.java new file mode 100644 index 00000000..f4816f3b --- /dev/null +++ b/src/de/lmu/ifi/dbs/elki/math/statistics/StudentDistribution.java @@ -0,0 +1,186 @@ +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) 2011 +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 java.util.HashMap; +import java.util.Map; + +/** + * 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 Map<Integer, Map<Double, Double>> tValues = new HashMap<Integer, Map<Double, Double>>(); + + 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; + } + Map<Double, Double> 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) { + Map<Double, Double> map = new HashMap<Double, Double>(); + 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); + } +}
\ No newline at end of file |