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MATH-1021 

Reordering can prevent some overflow occurrences (fix suggested by
Brian Bloniarz).
Added unit test.


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1512546 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Gilles Sadowski 2013-08-10 00:57:48 +00:00
parent 6d66a863b5
commit f1467e45ab
4 changed files with 21 additions and 1 deletions
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3
pom.xml
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@ -150,6 +150,9 @@
<contributor> <contributor>
<name>Michael Bjorkegren</name> <name>Michael Bjorkegren</name>
</contributor> </contributor>
<contributor>
<name>Brian Bloniarz</name>
</contributor>
<contributor> <contributor>
<name>John Bollinger</name> <name>John Bollinger</name>
</contributor> </contributor>

3
src/changes/changes.xml
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@ -51,6 +51,9 @@ If the output is not quite correct, check for invisible trailing spaces!
</properties> </properties>
<body> <body>
<release version="x.y" date="TBD" description="TBD"> <release version="x.y" date="TBD" description="TBD">
<action dev="erans" type="fix" issue="MATH-1021" due-to="Brian Bloniarz">
Fixed overflow in "HypergeometricDistribution".
</action>
<action dev="erans" type="fix" issue="MATH-1020"> <action dev="erans" type="fix" issue="MATH-1020">
Fixed "nextPermutation" method (in "o.a.c.m.random.RandomDataGenerator"). Fixed "nextPermutation" method (in "o.a.c.m.random.RandomDataGenerator").
This bug does not affect applications using a previous version of This bug does not affect applications using a previous version of

2
src/main/java/org/apache/commons/math3/distribution/HypergeometricDistribution.java
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@ -265,7 +265,7 @@ public class HypergeometricDistribution extends AbstractIntegerDistribution {
* size {@code n}, the mean is {@code n * m / N}. * size {@code n}, the mean is {@code n * m / N}.
*/ */
public double getNumericalMean() { public double getNumericalMean() {
return (double) (getSampleSize() * getNumberOfSuccesses()) / (double) getPopulationSize(); return getSampleSize() * (getNumberOfSuccesses() / (double) getPopulationSize());
} }
/** /**

14
src/test/java/org/apache/commons/math3/distribution/HypergeometricDistributionTest.java
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@ -284,4 +284,18 @@ public class HypergeometricDistributionTest extends IntegerDistributionAbstractT
double upper = 1.0 - dist.cumulativeProbability(k) + dist.probability(k); double upper = 1.0 - dist.cumulativeProbability(k) + dist.probability(k);
Assert.assertTrue(Precision.compareTo(1.0, upper, 1) == 0); Assert.assertTrue(Precision.compareTo(1.0, upper, 1) == 0);
} }
@Test
public void testMath1021() {
final int N = 43130568;
final int m = 42976365;
final int n = 50;
final HypergeometricDistribution dist = new HypergeometricDistribution(N, m, n);
for (int i = 0; i < 100; i++) {
final int sample = dist.sample();
Assert.assertTrue("sample=" + sample, 0 <= sample);
Assert.assertTrue("sample=" + sample, sample <= n);
}
}
} }