Recent changes to bugs

Disabled concurrency in FloatFFT_2D for size >= 64K

Laurent Bourgès — Thu, 16 Feb 2012 08:15:56 -0000

This is related to the FloatFFT_2D constructor that defines the useThreads variable: rows x columns > java int maximum values (32-bit signed 2,147,483,647)

Here is the trivial fix (convert int to long):

/**
* Creates new instance of FloatFFT_2D.
*
* @param rows number of rows
* @param columns number of columns
*/
public FloatFFT_2D(int rows, int columns) {
if (rows <= 1 || columns <= 1) {
throw new IllegalArgumentException("rows and columns must be greater than 1");
}
this.rows = rows;
this.columns = columns;

// fix integer capacity for rows = columns = 65536 !
if (((long)rows * columns) >= ConcurrencyUtils.getThreadsBeginN_2D()) {
this.useThreads = true;
}
...
}

Could you check and fix that bug anywhere it could happen (xxxFFT_2D, xxxFFT_3D ...) ?

FloatFFT_2D.realForward(float[][]) hangs for size >= 8K

Laurent Bourgès — Thu, 16 Feb 2012 08:14:50 -0000

This is related to FFT 1D concurrency thresholds whereas all threads are already busy within FloatFFT_2D.realForward().

As a workaround, I explicitly set these thresholds to INFINITY to disable FFT 1D parallelism:
// JTransforms: disable FFT_1D parallelism:
ConcurrencyUtils.setThreadsBeginN_1D_FFT_2Threads(Integer.MAX_VALUE);
ConcurrencyUtils.setThreadsBeginN_1D_FFT_4Threads(Integer.MAX_VALUE);

Maybe JTransforms could automatically disable FFT 1D parallelism when FFT 2D are computed ...

I propose that the FloatFFT_2D constructor which instanciate FloatFFT_1D objects (row/columns) define a flag useThreads = false in order to disable concurrency in such cases ...

[rev 25] FloatFFT_2D.realForwardFull of data with 6 columns

Wed, 06 Jul 2011 02:49:21 -0000

This is the same bug as #3355237, for the single precision (float) version of the 2d-FFT.

[rev 25] DoubleFFT_2D.realForwardFull of data with 6 columns

Wed, 06 Jul 2011 02:47:30 -0000

The following unit tests fail (see attached report)
- DoubleFFT_2DTest.testRealForwardFull1dinput
- DoubleFFT_2DTest.testRealInverseFullScaled1dinput
- DoubleFFT_2DTest.testRealInverseFullUnscaled1dinput
for the following data
- number of rows = any
- number of columns = 6
- multithreaded version of the algorithm.
Note that the first wrong value corresponds to index [6 * rows + 1]. Expected value 0. It seems that data with number of rows which are a multiple of 6 are not affected.

[rev 23] FloatFFT_3D.realForward fails the unit tests

Tue, 05 Jul 2011 07:12:15 -0000

All invocations of FloatFFT_3DTest.testRealForward1fInput and FloatFFT_3DTest.testRealForward3fInput fail (see attached report).

3d real FFT fails

Sat, 02 Jul 2011 16:35:37 -0000

Unit tests
- DoubleFFT_3DTest.testRealForward(double[]),
- DoubleFFT_3DTest.testRealForward(double[][][]),
both fail. This a a real bug, not an accuracy issue.