Package org.apfloat.aparapi

Class ColumnTwoPassFNTStrategy

java.lang.Object

org.apfloat.internal.AbstractStepFNTStrategy

org.apfloat.internal.TwoPassFNTStrategy

org.apfloat.aparapi.ColumnTwoPassFNTStrategy

All Implemented Interfaces:

Parallelizable, NTTStrategy

public class ColumnTwoPassFNTStrategy
extends TwoPassFNTStrategy

Two-pass NTT implementation that processes the data in the columns of the matrix.

This transform only works together with an NTTStepStrategy implementation that processes the data in columns instead of rows.

Note that if the data size is too big compared to the maximum available memory then the data is read from disk in too thin slices and the level of parallelism may become too small for the GPU, ruining the performance. The GPU global size i.e. the number of columns read from the data matrix to memory at one time should be at least 1024.

Since:

1.8.3

Version:

1.8.3

Field Summary

Fields inherited from class org.apfloat.internal.AbstractStepFNTStrategy

stepStrategy

Constructor Summary

Constructors

Constructor	Description
ColumnTwoPassFNTStrategy(NTTStepStrategy stepStrategy)	Basic constructor.

Method Summary

Modifier and Type	Method	Description
protected ArrayAccess	getColumns(DataStorage dataStorage, int startColumn, int columns, int rows)	Get a block of column data.
protected ArrayAccess	getRows(DataStorage dataStorage, int startRow, int rows, int columns)	Get a block of row data.
protected void	multiplyElements(ArrayAccess arrayAccess, int startRow, int startColumn, int rows, int columns, long length, long totalTransformLength, boolean isInverse, int modulus)	Multiply each matrix element (i, j) by wi * j / totalTransformLength.

Methods inherited from class org.apfloat.internal.TwoPassFNTStrategy

inverseTransform, transform, transformColumns, transformRows

Methods inherited from class org.apfloat.internal.AbstractStepFNTStrategy

getTransformLength, inverseTransform, transform

Methods inherited from class java.lang.Object

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

Constructor Detail

ColumnTwoPassFNTStrategy

public ColumnTwoPassFNTStrategy(NTTStepStrategy stepStrategy)

Basic constructor.

Parameters:

stepStrategy - A step strategy that can process data in columns.

Method Detail

getColumns

protected ArrayAccess getColumns(DataStorage dataStorage,
                                 int startColumn,
                                 int columns,
                                 int rows)

Description copied from class: TwoPassFNTStrategy

Get a block of column data. The data may be transposed, depending on the implementation.

Overrides:

getColumns in class TwoPassFNTStrategy

Parameters:

dataStorage - The data storage.

startColumn - The starting column where data is read.

columns - The number of columns of data to read.

rows - The number of rows of data to read. This should be equivalent to n₁, number of rows in the matrix.

Returns:

Access to an array of size columns x rows containing the data.

getRows

protected ArrayAccess getRows(DataStorage dataStorage,
                              int startRow,
                              int rows,
                              int columns)

Description copied from class: TwoPassFNTStrategy

Get a block of row data. The data may be transposed, depending on the implementation.

Overrides:

getRows in class TwoPassFNTStrategy

Parameters:

dataStorage - The data storage.

startRow - The starting row where data is read.

rows - The number of rows of data to read.

columns - The number of columns of data to read. This should be equivalent to n₂, number of columns in the matrix.

Returns:

Access to an array of size columns x rows containing the data.

multiplyElements

protected void multiplyElements(ArrayAccess arrayAccess,
                                int startRow,
                                int startColumn,
                                int rows,
                                int columns,
                                long length,
                                long totalTransformLength,
                                boolean isInverse,
                                int modulus)

Description copied from class: TwoPassFNTStrategy

Multiply each matrix element (i, j) by wi * j / totalTransformLength. The matrix size is n₁ x n₂.

Overrides:

multiplyElements in class TwoPassFNTStrategy

Parameters:

arrayAccess - The memory array to multiply.

startRow - Which row in the whole matrix the starting row in the arrayAccess is.

startColumn - Which column in the whole matrix the starting column in the arrayAccess is.

rows - The number of rows in the arrayAccess to multiply.

columns - The number of columns in the matrix (= n₂).

length - The length of data in the matrix being transformed.

totalTransformLength - The total transform length, for the scaling factor. Used only for the inverse case.

isInverse - If the multiplication is done for the inverse transform or not.

modulus - Index of the modulus.