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org.apache.mahout.math.map
public class: PrimeFinder [javadoc | source]
java.lang.Object
   org.apache.mahout.math.map.PrimeFinder
Not of interest for users; only for implementors of hashtables. Used to keep hash table capacities prime numbers.

Choosing prime numbers as hash table capacities is a good idea to keep them working fast, particularly under hash table expansions.

However, JDK 1.2, JGL 3.1 and many other toolkits do nothing to keep capacities prime. This class provides efficient means to choose prime capacities.

Choosing a prime is O(log 300) (binary search in a list of 300 int's). Memory requirements: 1 KB static memory.
Field Summary
public static final  int largestPrime    The largest prime this class can generate; currently equal to Integer.MAX_VALUE
Method from org.apache.mahout.math.map.PrimeFinder Summary:
nextPrime
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from org.apache.mahout.math.map.PrimeFinder Detail:
 public static int nextPrime(int desiredCapacity) 
    Returns a prime number which is >= desiredCapacity and very close to desiredCapacity (within 11% if desiredCapacity >= 1000).