| /* |
| * 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.numbers.gamma; |
| |
| import org.junit.jupiter.api.Assertions; |
| import org.junit.jupiter.api.Test; |
| |
| /** |
| * Tests for {@link RegularizedGamma}. |
| */ |
| public class RegularizedGammaTest { |
| @Test |
| public void testRegularizedGammaNanPositive() { |
| testRegularizedGamma(Double.NaN, Double.NaN, 1.0); |
| } |
| |
| @Test |
| public void testRegularizedGammaPositiveNan() { |
| testRegularizedGamma(Double.NaN, 1.0, Double.NaN); |
| } |
| |
| @Test |
| public void testRegularizedGammaNegativePositive() { |
| testRegularizedGamma(Double.NaN, -1.5, 1.0); |
| } |
| |
| @Test |
| public void testRegularizedGammaPositiveNegative() { |
| testRegularizedGamma(Double.NaN, 1.0, -1.0); |
| } |
| |
| @Test |
| public void testRegularizedGammaZeroPositive() { |
| testRegularizedGamma(Double.NaN, 0.0, 1.0); |
| } |
| |
| @Test |
| public void testRegularizedGammaPositiveZero() { |
| testRegularizedGamma(0.0, 1.0, 0.0); |
| } |
| |
| @Test |
| public void testRegularizedGammaPositivePositive() { |
| testRegularizedGamma(0.632120558828558, 1.0, 1.0); |
| } |
| |
| @Test |
| public void testRegularizedGammaPWithACloseToZero() { |
| // Creates a case where the regularized gamma P series is evaluated and the |
| // result is outside the expected bounds of [0, 1]. This should be clipped to 1.0. |
| final double a = 1e-18; |
| // x must force use of the series in regularized gamma P using x < a + 1 |
| final double x = 0.5; |
| testRegularizedGamma(1.0, a, x); |
| } |
| |
| @Test |
| public void testRegularizedGammaPWithAVeryCloseToZero() { |
| // Creates a case where the partial sum is infinite due to inclusion of 1 / a |
| final double a = Double.MIN_VALUE; |
| // x must force use of the series in regularized gamma P using x < a + 1 |
| final double x = 0.5; |
| testRegularizedGamma(1.0, a, x); |
| } |
| |
| private void testRegularizedGamma(double expected, double a, double x) { |
| double actualP = RegularizedGamma.P.value(a, x); |
| double actualQ = RegularizedGamma.Q.value(a, x); |
| Assertions.assertEquals(expected, actualP, 1e-15); |
| Assertions.assertEquals(actualP, 1 - actualQ, 1e-15); |
| } |
| |
| @Test |
| public void testRegularizedGammaMaxIterationsExceededThrows() { |
| final double a = 1.0; |
| final double x = 1.0; |
| // OK without |
| Assertions.assertEquals(0.632120558828558, RegularizedGamma.P.value(a, x), 1e-15); |
| |
| final int maxIterations = 3; |
| Assertions.assertThrows(ArithmeticException.class, () -> |
| RegularizedGamma.P.value(a, x, 1e-15, maxIterations)); |
| } |
| } |