Package org.apfloat.internal

Class StepCarryCRTStrategy

java.lang.Object

org.apfloat.internal.StepCarryCRTStrategy

All Implemented Interfaces:

Parallelizable, CarryCRTStrategy

public class StepCarryCRTStrategy
extends Object
implements CarryCRTStrategy, Parallelizable

Class for performing the final step of a three-modulus Number Theoretic Transform based convolution. Works with blocks of data.

The algorithm is parallelized for multiprocessor computers, if the data fits in memory.

The parallelization works so that the carry-CRT is done in blocks in parallel. As a final step, a second pass is done through the data set to propagate the carries from one block to the next.

All access to this class must be externally synchronized.

Since:

1.7.0

Version:

1.9.0

Author:

Mikko Tommila

See Also:

• CarryCRTStepStrategy

Constructor Summary

Constructors

Constructor	Description
StepCarryCRTStrategy(int radix)	Creates a carry-CRT object using the specified radix.

Method Summary

Modifier and Type	Method	Description
DataStorage	carryCRT(DataStorage resultMod0, DataStorage resultMod1, DataStorage resultMod2, long resultSize)	Calculate the final result of a three-NTT convolution.
protected <T> ParallelRunnable	createCarryCRTParallelRunnable(Class<T> elementArrayType, DataStorage resultMod0, DataStorage resultMod1, DataStorage resultMod2, DataStorage dataStorage, long size, long resultSize)	Create a ParallelRunnable object for doing the carry-CRT in parallel.

Methods inherited from class java.lang.Object

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

Constructor Details

StepCarryCRTStrategy

public StepCarryCRTStrategy(int radix)

Creates a carry-CRT object using the specified radix.

Parameters:

radix - The radix that will be used.

Method Details

carryCRT

public DataStorage carryCRT(DataStorage resultMod0,
 DataStorage resultMod1,
 DataStorage resultMod2,
 long resultSize)
                     throws ApfloatRuntimeException

Calculate the final result of a three-NTT convolution.

Performs a Chinese Remainder Theorem (CRT) on each element of the three result data sets to get the result of each element modulo the product of the three moduli. Then it calculates the carries to get the final result.

Note that the return value's initial word may be zero or non-zero, depending on how large the result is.

Assumes that MODULUS[0] > MODULUS[1] > MODULUS[2].

Specified by:

carryCRT in interface CarryCRTStrategy

Parameters:

resultMod0 - The result modulo MODULUS[0].

resultMod1 - The result modulo MODULUS[1].

resultMod2 - The result modulo MODULUS[2].

resultSize - The number of elements needed in the final result.

Returns:

The final result with the CRT performed and the carries calculated.

Throws:

ApfloatRuntimeException

createCarryCRTParallelRunnable

protected <T> ParallelRunnable createCarryCRTParallelRunnable(Class<T> elementArrayType,
 DataStorage resultMod0,
 DataStorage resultMod1,
 DataStorage resultMod2,
 DataStorage dataStorage,
 long size,
 long resultSize)

Create a ParallelRunnable object for doing the carry-CRT in parallel.

Type Parameters:

T - The element array type used.

Parameters:

elementArrayType - The element array type used.

resultMod0 - The result modulo MODULUS[0].

resultMod1 - The result modulo MODULUS[1].

resultMod2 - The result modulo MODULUS[2].

dataStorage - The destination data storage of the computation.

size - The number of elements in the whole data set.

resultSize - The number of elements needed in the final result.

Returns:

An suitable object for performing the carry-CRT in parallel.