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[MATH-1068] Changed integer calculations with potential overflows to long. 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1548907 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Thomas Neidhart 2013-12-07 13:08:06 +00:00
parent 8e5867eda8
commit e42da5d9d2
1 changed files with 25 additions and 14 deletions
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39
src/main/java/org/apache/commons/math3/stat/correlation/KendallsCorrelation.java
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@ -160,7 +160,7 @@ public class KendallsCorrelation {
} }
final int n = xArray.length; final int n = xArray.length;
final long numPairs = n * (n - 1l) / 2l; final long numPairs = sum(n - 1);
@SuppressWarnings("unchecked") @SuppressWarnings("unchecked")
Pair<Double, Double>[] pairs = new Pair[n]; Pair<Double, Double>[] pairs = new Pair[n];
@ -175,10 +175,10 @@ public class KendallsCorrelation {
} }
}); });
int tiedXPairs = 0; long tiedXPairs = 0;
int tiedXYPairs = 0; long tiedXYPairs = 0;
int consecutiveXTies = 1; long consecutiveXTies = 1;
int consecutiveXYTies = 1; long consecutiveXYTies = 1;
Pair<Double, Double> prev = pairs[0]; Pair<Double, Double> prev = pairs[0];
for (int i = 1; i < n; i++) { for (int i = 1; i < n; i++) {
final Pair<Double, Double> curr = pairs[i]; final Pair<Double, Double> curr = pairs[i];
@ -187,19 +187,19 @@ public class KendallsCorrelation {
if (curr.getSecond().equals(prev.getSecond())) { if (curr.getSecond().equals(prev.getSecond())) {
consecutiveXYTies++; consecutiveXYTies++;
} else { } else {
tiedXYPairs += consecutiveXYTies * (consecutiveXYTies - 1) / 2; tiedXYPairs += sum(consecutiveXYTies - 1);
consecutiveXYTies = 1; consecutiveXYTies = 1;
} }
} else { } else {
tiedXPairs += consecutiveXTies * (consecutiveXTies - 1) / 2; tiedXPairs += sum(consecutiveXTies - 1);
consecutiveXTies = 1; consecutiveXTies = 1;
tiedXYPairs += consecutiveXYTies * (consecutiveXYTies - 1) / 2; tiedXYPairs += sum(consecutiveXYTies - 1);
consecutiveXYTies = 1; consecutiveXYTies = 1;
} }
prev = curr; prev = curr;
} }
tiedXPairs += consecutiveXTies * (consecutiveXTies - 1) / 2; tiedXPairs += sum(consecutiveXTies - 1);
tiedXYPairs += consecutiveXYTies * (consecutiveXYTies - 1) / 2; tiedXYPairs += sum(consecutiveXYTies - 1);
int swaps = 0; int swaps = 0;
@SuppressWarnings("unchecked") @SuppressWarnings("unchecked")
@ -239,23 +239,34 @@ public class KendallsCorrelation {
pairsDestination = pairsTemp; pairsDestination = pairsTemp;
} }
int tiedYPairs = 0; long tiedYPairs = 0;
int consecutiveYTies = 1; long consecutiveYTies = 1;
prev = pairs[0]; prev = pairs[0];
for (int i = 1; i < n; i++) { for (int i = 1; i < n; i++) {
final Pair<Double, Double> curr = pairs[i]; final Pair<Double, Double> curr = pairs[i];
if (curr.getSecond().equals(prev.getSecond())) { if (curr.getSecond().equals(prev.getSecond())) {
consecutiveYTies++; consecutiveYTies++;
} else { } else {
tiedYPairs += consecutiveYTies * (consecutiveYTies - 1) / 2; tiedYPairs += sum(consecutiveYTies - 1);
consecutiveYTies = 1; consecutiveYTies = 1;
} }
prev = curr; prev = curr;
} }
tiedYPairs += consecutiveYTies * (consecutiveYTies - 1) / 2; tiedYPairs += sum(consecutiveYTies - 1);
final long concordantMinusDiscordant = numPairs - tiedXPairs - tiedYPairs + tiedXYPairs - 2 * swaps; final long concordantMinusDiscordant = numPairs - tiedXPairs - tiedYPairs + tiedXYPairs - 2 * swaps;
final double nonTiedPairsMultiplied = (numPairs - tiedXPairs) * (double) (numPairs - tiedYPairs); final double nonTiedPairsMultiplied = (numPairs - tiedXPairs) * (double) (numPairs - tiedYPairs);
return concordantMinusDiscordant / FastMath.sqrt(nonTiedPairsMultiplied); return concordantMinusDiscordant / FastMath.sqrt(nonTiedPairsMultiplied);
} }
/**
* Returns the sum of the number from 1 .. n according to Gauss' summation formula:
* \[ \sum\limits_{k=1}^n k = \frac{n(n + 1)}{2} \]
*
* @param n the summation end
* @return the sum of the number from 1 to n
*/
private static long sum(long n) {
return n * (n + 1) / 2l;
}
} }