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Corrected inverseCumulativeProbability(0). 

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/math/trunk@141417 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Phil Steitz 2004-07-25 16:29:25 +00:00
parent bec758a4e5
commit b134bf41f7
4 changed files with 29 additions and 11 deletions
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7
src/java/org/apache/commons/math/distribution/BinomialDistributionImpl.java
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@ -24,7 +24,7 @@ import org.apache.commons.math.util.MathUtils;
/**
* The default implementation of {@link BinomialDistribution}.
*
* @version $Revision: 1.17 $ $Date: 2004/07/23 05:22:36 $
* @version $Revision: 1.18 $ $Date: 2004/07/25 16:29:24 $
*/
public class BinomialDistributionImpl
extends AbstractDiscreteDistribution
@ -162,6 +162,9 @@ public class BinomialDistributionImpl
/**
* For this distribution, X, this method returns the largest x, such
* that P(X &le; x) &le; <code>p</code>.
* <p>
* Returns <code>-1</code> for p=0 and <code>Integer.MAX_VALUE</code> for
* p=1.
*
* @param p the desired probability
* @return the largest x such that P(X &le; x) <= p
@ -172,7 +175,7 @@ public class BinomialDistributionImpl
public int inverseCumulativeProbability(final double p) throws MathException {
// handle extreme values explicitly
if (p == 0) {
return 0;
return -1;
}
if (p == 1) {
return Integer.MAX_VALUE;

21
src/java/org/apache/commons/math/distribution/DiscreteDistribution.java
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@ -20,7 +20,7 @@ import org.apache.commons.math.MathException;
/**
* Base interface for various discrete distributions.
*
* @version $Revision: 1.15 $ $Date: 2004/06/23 16:26:15 $
* @version $Revision: 1.16 $ $Date: 2004/07/25 16:29:24 $
*/
public interface DiscreteDistribution {
/**
@ -51,11 +51,26 @@ public interface DiscreteDistribution {
double cumulativeProbability(int x0, int x1) throws MathException;
/**
* For this distribution, X, this method returns the largest x such that P(X &le; x) <= p.
* For this distribution, X, this method returns the largest x such that
* P(X &le; x) <= p.
* <p>
* Note that this definition implies: <ul>
* <li> If there is a minimum value, <code>m</code>, with postive
* probablility under (the density of) X, then <code>m - 1</code> is
* returned by <code>inverseCumulativeProbability(0).</code> If there is
* no such value <code>m, Integer.MIN_VALUE</code> is
* returned.</li>
* <li> If there is a maximum value, <code>M</code>, such that
* P(X &le; M) =1, then <code>M</code> is returned by
* <code>inverseCumulativeProbability(1).</code>
* If there is no such value, <code>M, Integer.MAX_VALUE</code> is
* returned.</li></ul>
*
* @param p the cumulative probability.
* @return x.
* @return the largest x such that P(X &le; x) <= p
* @throws MathException if the inverse cumulative probability can not be
* computed due to convergence or other numerical errors.
* @throws IllegalArgumentException if p is not between 0 and 1 (inclusive)
*/
int inverseCumulativeProbability(double p) throws MathException;
}

4
src/test/org/apache/commons/math/distribution/BinomialDistributionTest.java
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@ -20,7 +20,7 @@ package org.apache.commons.math.distribution;
* Extends DiscreteDistributionAbstractTest. See class javadoc for
* DiscreteDistributionAbstractTest for details.
*
* @version $Revision: 1.14 $ $Date: 2004/07/23 05:22:36 $
* @version $Revision: 1.15 $ $Date: 2004/07/25 16:29:25 $
*/
public class BinomialDistributionTest extends DiscreteDistributionAbstractTest {
@ -69,7 +69,7 @@ public class BinomialDistributionTest extends DiscreteDistributionAbstractTest {
/** Creates the default inverse cumulative probability density test expected values */
public int[] makeInverseCumulativeTestValues() {
return new int[] {0,1, 2, 3, 4, 4, 9, 9, 9, 8, 8, Integer.MAX_VALUE};
return new int[] {-1, 1, 2, 3, 4, 4, 9, 9, 9, 8, 8, Integer.MAX_VALUE};
}
//----------------- Additional test cases ---------------------------------

8
src/test/org/apache/commons/math/distribution/HypergeometricDistributionTest.java
View File

@ -21,7 +21,7 @@ package org.apache.commons.math.distribution;
* Extends DiscreteDistributionAbstractTest. See class javadoc for
* DiscreteDistributionAbstractTest for details.
*
* @version $Revision: 1.11 $ $Date: 2004/05/11 02:12:11 $
* @version $Revision: 1.12 $ $Date: 2004/07/25 16:29:25 $
*/
public class HypergeometricDistributionTest extends DiscreteDistributionAbstractTest {
@ -64,13 +64,13 @@ public class HypergeometricDistributionTest extends DiscreteDistributionAbstract
/** Creates the default inverse cumulative probability test input values */
public double[] makeInverseCumulativeTestPoints() {
return new double[] {0.001d, 0.010d, 0.025d, 0.050d, 0.100d, 0.999d,
0.990d, 0.975d, 0.950d, 0.900d};
return new double[] {0d, 0.001d, 0.010d, 0.025d, 0.050d, 0.100d, 0.999d,
0.990d, 0.975d, 0.950d, 0.900d, 1d};
}
/** Creates the default inverse cumulative probability density test expected values */
public int[] makeInverseCumulativeTestValues() {
return new int[] {-1, 0, 0, 0, 0, 4, 3, 3, 3, 3};
return new int[] {-1, -1, 0, 0, 0, 0, 4, 3, 3, 3, 3, 5};
}
//-------------------- Additional test cases ------------------------------