MATH-1356 Handle special cases for which the computation would otherwise produce NaN. Thanks to Thomas Lacroix for the report.
Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo Commit: http://git-wip-us.apache.org/repos/asf/commons-math/commit/0880a21c Tree: http://git-wip-us.apache.org/repos/asf/commons-math/tree/0880a21c Diff: http://git-wip-us.apache.org/repos/asf/commons-math/diff/0880a21c Branch: refs/heads/develop Commit: 0880a21c56cec1a2442b5123c3845bfc99e83a7f Parents: 3066a80 Author: Gilles <er...@apache.org> Authored: Tue Apr 19 00:27:32 2016 +0200 Committer: Gilles <er...@apache.org> Committed: Tue Apr 19 00:27:32 2016 +0200 ---------------------------------------------------------------------- .../distribution/SaddlePointExpansion.java | 6 +++++ .../HypergeometricDistributionTest.java | 26 ++++++++++++++++++++ 2 files changed, 32 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/commons-math/blob/0880a21c/src/main/java/org/apache/commons/math4/distribution/SaddlePointExpansion.java ---------------------------------------------------------------------- diff --git a/src/main/java/org/apache/commons/math4/distribution/SaddlePointExpansion.java b/src/main/java/org/apache/commons/math4/distribution/SaddlePointExpansion.java index 01b0f65..aea0e3c 100644 --- a/src/main/java/org/apache/commons/math4/distribution/SaddlePointExpansion.java +++ b/src/main/java/org/apache/commons/math4/distribution/SaddlePointExpansion.java @@ -159,6 +159,9 @@ final class SaddlePointExpansion { } ret = s1; } else { + if (x == 0) { + return mu; + } ret = x * FastMath.log(x / mu) + mu - x; } return ret; @@ -180,6 +183,9 @@ final class SaddlePointExpansion { if (p < 0.1) { ret = -getDeviancePart(n, n * q) - n * p; } else { + if (n == 0) { + return 0; + } ret = n * FastMath.log(q); } } else if (x == n) { http://git-wip-us.apache.org/repos/asf/commons-math/blob/0880a21c/src/test/java/org/apache/commons/math4/distribution/HypergeometricDistributionTest.java ---------------------------------------------------------------------- diff --git a/src/test/java/org/apache/commons/math4/distribution/HypergeometricDistributionTest.java b/src/test/java/org/apache/commons/math4/distribution/HypergeometricDistributionTest.java index e12c5b4..7e7ce8c 100644 --- a/src/test/java/org/apache/commons/math4/distribution/HypergeometricDistributionTest.java +++ b/src/test/java/org/apache/commons/math4/distribution/HypergeometricDistributionTest.java @@ -312,6 +312,32 @@ public class HypergeometricDistributionTest extends IntegerDistributionAbstractT } @Test + public void testZeroTrial() { + final int n = 11; // population + final int m = 4; // successes in population + final int s = 0; // number of trials + + final HypergeometricDistribution dist = new HypergeometricDistribution(n, m, 0); + + for (int i = 1; i <= n; i++) { + final double p = dist.probability(i); + Assert.assertEquals("p=" + p, 0, p, 0d); + } + } + + @Test + public void testMath1356() { + final int n = 11; // population + final int m = 11; // successes in population + + for (int s = 0; s <= n; s++) { + final HypergeometricDistribution dist = new HypergeometricDistribution(n, m, s); + final double p = dist.probability(s); + Assert.assertEquals("p=" + p, 1, p, 0d); + } + } + + @Test public void testMath1021() { final int N = 43130568; final int m = 42976365;
