Package de.tilman_neumann.jml.factor.hart

Class Hart_Fast

java.lang.Object

de.tilman_neumann.jml.factor.FactorAlgorithm

de.tilman_neumann.jml.factor.hart.Hart_Fast

public class Hart_Fast
extends FactorAlgorithm

Pretty simple yet fast variant of Hart's one line factorizer. The main problem with this implementation is that we need to know to nature of test numbers. With doTDivFirst=false it is the fastest algorithm for hard semiprimes, but if the test numbers contain factors < cbrt(N), it will fail to find some of them. With doTDivFirst=true it will find all factors of any kind of numbers, but not extraordinarily fast. Hart_TDiv_Race fixes that problem and is faster for test numbers that contain factors < cbrt(N).

Field Summary

Fields inherited from class de.tilman_neumann.jml.factor.FactorAlgorithm

DEFAULT, NUM_PRIMES_FOR_31_BIT_TDIV, tdivLimit

Constructor Summary

Constructors

Constructor	Description
Hart_Fast(boolean doTDivFirst)	Full constructor.

Method Summary

Modifier and Type	Method	Description
long	findSingleFactor(long N)	Find a factor of long N.
BigInteger	findSingleFactor(BigInteger N)	Find a single factor of the given N, which is composite and odd.
String	getName()
static void	main(String[] args)	Test.

Methods inherited from class de.tilman_neumann.jml.factor.FactorAlgorithm

factor, factor, searchFactors

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Hart_Fast

public Hart_Fast(boolean doTDivFirst)

Full constructor.

Parameters:

doTDivFirst - If true then trial division is done before the Lehman loop. This is recommended if arguments N are known to have factors < cbrt(N) frequently.

Method Detail

getName

public String getName()

Specified by:

getName in class FactorAlgorithm

Returns:

The name of the algorithm, possibly including important parameters.

findSingleFactor

public BigInteger findSingleFactor(BigInteger N)

Description copied from class: FactorAlgorithm

Find a single factor of the given N, which is composite and odd.

Specified by:

findSingleFactor in class FactorAlgorithm

Returns:

factor

findSingleFactor

public long findSingleFactor(long N)

Find a factor of long N.

Parameters:

N -

Returns:

factor of N

main

public static void main(String[] args)

Test.

Parameters:

args - ignored