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MATH-790: Patch applied to fix the overflow issue. 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1348024 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Mikkel Meyer Andersen 2012-06-08 11:04:11 +00:00
parent a40ad8af53
commit 33169dcf75
2 changed files with 15 additions and 3 deletions
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6
src/main/java/org/apache/commons/math3/stat/inference/MannWhitneyUTest.java
View File

@ -170,11 +170,11 @@ public class MannWhitneyUTest {
final int n2)
throws ConvergenceException, MaxCountExceededException {
final int n1n2prod = n1 * n2;
final double n1n2prod = n1 * n2;
// http://en.wikipedia.org/wiki/Mann%E2%80%93Whitney_U#Normal_approximation
final double EU = (double) n1n2prod / 2.0;
final double VarU = (double) (n1n2prod * (n1 + n2 + 1)) / 12.0;
final double EU = n1n2prod / 2.0;
final double VarU = n1n2prod * (n1 + n2 + 1) / 12.0;
final double z = (Umin - EU) / FastMath.sqrt(VarU);

12
src/test/java/org/apache/commons/math3/stat/inference/MannWhitneyUTestTest.java
View File

@ -100,4 +100,16 @@ public class MannWhitneyUTestTest {
// expected
}
}
@Test
public void testBigDataSet() throws Exception {
double[] d1 = new double[1500];
double[] d2 = new double[1500];
for (int i = 0; i < 1500; i++) {
d1[i] = 2 * i;
d2[i] = 2 * i + 1;
}
double result = testStatistic.mannWhitneyUTest(d1, d2);
Assert.assertTrue(result > 0.1);
}
}