org.apfloat.internal
Class LongFactor3NTTStrategy

java.lang.Object
  extended by org.apfloat.internal.LongElementaryModMath
      extended by org.apfloat.internal.LongModMath
          extended by org.apfloat.internal.LongFactor3NTTStrategy
All Implemented Interfaces:
NTTStrategy

public class LongFactor3NTTStrategy
extends LongModMath
implements NTTStrategy

A transform that implements a 3-point transform on top of another Number Theoretic Transform that does transforms of length 2n.

Version:
1.1
Author:
Mikko Tommila

Constructor Summary
LongFactor3NTTStrategy(NTTStrategy factor2Strategy)
          Creates a new factor-3 transform strategy on top of an existing transform.
 
Method Summary
 long getTransformLength(long size)
          Return the supported transform length for the specified data size.
 void inverseTransform(DataStorage dataStorage, int modulus, long totalTransformLength)
          Perform an inverse transform on the data.
 void transform(DataStorage dataStorage, int modulus)
          Perform a forward transform on the data.
 
Methods inherited from class org.apfloat.internal.LongModMath
createWTable, getForwardNthRoot, getInverseNthRoot, modDivide, modInverse, modPow, negate
 
Methods inherited from class org.apfloat.internal.LongElementaryModMath
getModulus, modAdd, modMultiply, modSubtract, setModulus
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

LongFactor3NTTStrategy

public LongFactor3NTTStrategy(NTTStrategy factor2Strategy)
Creates a new factor-3 transform strategy on top of an existing transform. The underlying transform needs to be capable of only doing transforms of length 2n.

Parameters:
factor2Strategy - The underlying transformation strategy, that can be capable of only doing radix-2 transforms.
Method Detail

transform

public void transform(DataStorage dataStorage,
                      int modulus)
               throws ApfloatRuntimeException
Description copied from interface: NTTStrategy
Perform a forward transform on the data.

Multiple moduli can be used, if the convolution algorithm uses the Chinese Remainder Theorem to calculate the final result.

Specified by:
transform in interface NTTStrategy
Parameters:
dataStorage - The data to be transformed.
modulus - Number of modulus to use (in case the transform supports multiple moduli).
Throws:
ApfloatRuntimeException

inverseTransform

public void inverseTransform(DataStorage dataStorage,
                             int modulus,
                             long totalTransformLength)
                      throws ApfloatRuntimeException
Description copied from interface: NTTStrategy
Perform an inverse transform on the data.

Multiple moduli can be used, if the convolution algorithm uses the Chinese Remainder Theorem to calculate the final result.

Specified by:
inverseTransform in interface NTTStrategy
Parameters:
dataStorage - The data to be transformed.
modulus - Number of modulus to use (in case the transform supports multiple moduli).
totalTransformLength - Total transform length; the final result elements are divided by this value.
Throws:
ApfloatRuntimeException

getTransformLength

public long getTransformLength(long size)
Description copied from interface: NTTStrategy
Return the supported transform length for the specified data size.

Specified by:
getTransformLength in interface NTTStrategy
Parameters:
size - Length of the data to be transformed.
Returns:
Length of the transform needed by this transform.