Class Lehman_Simple

java.lang.Object
de.tilman_neumann.jml.factor.FactorAlgorithm
de.tilman_neumann.jml.factor.lehman.Lehman_Simple

public class Lehman_Simple
extends FactorAlgorithm
Simple implementation of Lehmans factor algorithm, following https://programmingpraxis.com/2017/08/22/lehmans-factoring-algorithm/, using fast inverse trial division. This implementation is pretty slow, but useful for illustrating the basic algorithm. It may fail for N>=47 bit where 4*k*N produces a long-overflow.
  • Field Summary

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

    NUM_PRIMES_FOR_31_BIT_TDIV, tdivLimit
  • Constructor Summary

    Constructors
    Constructor Description
    Lehman_Simple​(boolean doTDivFirst)
    Full constructor.
  • Method Summary

    Modifier and Type Method Description
    long findSingleFactor​(long N)  
    java.math.BigInteger findSingleFactor​(java.math.BigInteger N)
    Find a single factor of the given N, which is composite and odd.
    java.lang.String getName()  

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

    factor, factor, getDefault, searchFactors

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • Lehman_Simple

      public Lehman_Simple​(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 Details

    • getName

      public java.lang.String getName()
      Specified by:
      getName in class FactorAlgorithm
      Returns:
      The name of the algorithm, possibly including important parameters.
    • findSingleFactor

      public java.math.BigInteger findSingleFactor​(java.math.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
      Parameters:
      N - number to be factored.
      Returns:
      factor
    • findSingleFactor

      public long findSingleFactor​(long N)