| /* |
| * 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.statistics.distribution; |
| |
| import org.apache.commons.rng.UniformRandomProvider; |
| |
| /** |
| * Implementation of the constant real distribution. |
| */ |
| public class ConstantContinuousDistribution extends AbstractContinuousDistribution { |
| /** Constant value of the distribution. */ |
| private final double value; |
| |
| /** |
| * Create a constant real distribution with the given value. |
| * |
| * @param value Value of this distribution. |
| */ |
| public ConstantContinuousDistribution(double value) { |
| this.value = value; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public double density(double x) { |
| return x == value ? 1 : 0; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public double cumulativeProbability(double x) { |
| return x < value ? 0 : 1; |
| } |
| |
| /** {@inheritDoc} */ |
| @Override |
| public double inverseCumulativeProbability(final double p) { |
| if (p < 0 || |
| p > 1) { |
| throw new DistributionException(DistributionException.INVALID_PROBABILITY, p); |
| } |
| return value; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public double getMean() { |
| return value; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public double getVariance() { |
| return 0; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public double getSupportLowerBound() { |
| return value; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public double getSupportUpperBound() { |
| return value; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public boolean isSupportConnected() { |
| return true; |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @param rng Not used: distribution contains a single value. |
| * @return the value of the distribution. |
| */ |
| @Override |
| public ContinuousDistribution.Sampler createSampler(final UniformRandomProvider rng) { |
| return this::getSupportLowerBound; |
| } |
| } |