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Diffstat (limited to 'src/main/java/org/apache/commons/math/distribution/IntegerDistribution.java')
| -rw-r--r-- | src/main/java/org/apache/commons/math/distribution/IntegerDistribution.java | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math/distribution/IntegerDistribution.java b/src/main/java/org/apache/commons/math/distribution/IntegerDistribution.java new file mode 100644 index 0000000..096af17 --- /dev/null +++ b/src/main/java/org/apache/commons/math/distribution/IntegerDistribution.java @@ -0,0 +1,84 @@ +/* + * 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.math.distribution; + +import org.apache.commons.math.MathException; + +/** + * Interface for discrete distributions of integer-valued random variables. + * + * @version $Revision: 949535 $ $Date: 2010-05-30 19:00:15 +0200 (dim. 30 mai 2010) $ + */ +public interface IntegerDistribution extends DiscreteDistribution { + /** + * For a random variable X whose values are distributed according + * to this distribution, this method returns P(X = x). In other words, this + * method represents the probability mass function for the distribution. + * + * @param x the value at which the probability density function is evaluated. + * @return the value of the probability density function at x + */ + double probability(int x); + + /** + * For a random variable X whose values are distributed according + * to this distribution, this method returns P(X ≤ x). In other words, + * this method represents the probability distribution function, or PDF + * for the distribution. + * + * @param x the value at which the PDF is evaluated. + * @return PDF for this distribution. + * @throws MathException if the cumulative probability can not be + * computed due to convergence or other numerical errors. + */ + double cumulativeProbability(int x) throws MathException; + + /** + * For this distribution, X, this method returns P(x0 ≤ X ≤ x1). + * @param x0 the inclusive, lower bound + * @param x1 the inclusive, upper bound + * @return the cumulative probability. + * @throws MathException if the cumulative probability can not be + * computed due to convergence or other numerical errors. + * @throws IllegalArgumentException if x0 > x1 + */ + double cumulativeProbability(int x0, int x1) throws MathException; + + /** + * For this distribution, X, this method returns the largest x such that + * P(X ≤ x) <= p. + * <p> + * Note that this definition implies: <ul> + * <li> If there is a minimum value, <code>m</code>, with positive + * probability under (the density of) X, then <code>m - 1</code> is + * returned by <code>inverseCumulativeProbability(0).</code> If there is + * no such value <code>m, Integer.MIN_VALUE</code> is + * returned.</li> + * <li> If there is a maximum value, <code>M</code>, such that + * P(X ≤ M) =1, then <code>M</code> is returned by + * <code>inverseCumulativeProbability(1).</code> + * If there is no such value, <code>M, Integer.MAX_VALUE</code> is + * returned.</li></ul></p> + * + * @param p the cumulative probability. + * @return the largest x such that P(X ≤ x) <= p + * @throws MathException if the inverse cumulative probability can not be + * computed due to convergence or other numerical errors. + * @throws IllegalArgumentException if p is not between 0 and 1 (inclusive) + */ + int inverseCumulativeProbability(double p) throws MathException; +} |