aherbert commented on a change in pull request #140: Bloomfilter updates2
URL:
https://github.com/apache/commons-collections/pull/140#discussion_r391789974
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File path:
src/main/java/org/apache/commons/collections4/bloomfilter/hasher/Shape.java
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@@ -312,32 +402,18 @@ public int getNumberOfItems() {
}
/**
- * Calculates the probability of false positives (AKA: {@code p} given
- * numberOfItems, numberofBits and numberOfHashFunctions. This is a method
so that
- * the calculation is consistent across all constructors.
+ * Calculates the probability of false positives ({@code p}) given
+ * numberOfItems ({@code n}), numberOfBits ({@code m}) and
numberOfHashFunctions ({@code k}).
+ * <pre>p = pow(1 - exp(-k / (m / n)), k)</pre>
+ *
+ * <p>This is the probability that a Bloom filter will return true for the
presence of an item
+ * when it does not contain the item.
*
* @return the probability of collision.
Review comment:
Is it the probability of false positives when the filter is at capacity
(contains n items)?
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