org.apache.lucene.util
Class MathUtil

java.lang.Object
  extended by org.apache.lucene.util.MathUtil

public final class MathUtil
extends Object

Math static utility methods.


Method Summary
static long gcd(long a, long b)
          Return the greatest common divisor of a and b, consistently with BigInteger.gcd(BigInteger).
static int log(long x, int base)
          Returns x <= 0 ? 0 : Math.floor(Math.log(x) / Math.log(base))
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

log

public static int log(long x,
                      int base)
Returns x <= 0 ? 0 : Math.floor(Math.log(x) / Math.log(base))

Parameters:
base - must be > 1

gcd

public static long gcd(long a,
                       long b)
Return the greatest common divisor of a and b, consistently with BigInteger.gcd(BigInteger).

NOTE: A greatest common divisor must be positive, but 2^64 cannot be expressed as a long although it is the GCD of Long.MIN_VALUE and 0 and the GCD of Long.MIN_VALUE and Long.MIN_VALUE. So in these 2 cases, and only them, this method will return Long.MIN_VALUE.



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