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.
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Field Summary
Fields inherited from class de.tilman_neumann.jml.factor.FactorAlgorithm
NUM_PRIMES_FOR_31_BIT_TDIV, tdivLimit
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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
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Constructor Details
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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.
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Method Details
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getName
public java.lang.String getName()- Specified by:
getName
in classFactorAlgorithm
- Returns:
- The name of the algorithm, possibly including important parameters.
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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 classFactorAlgorithm
- Parameters:
N
- number to be factored.- Returns:
- factor
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findSingleFactor
public long findSingleFactor(long N)
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