Re: Working patch for FFTW 3.0.x and Nd FFT's

[Paul Kienzle]

On Feb 17, 2004, at 5:00 PM, John W. Eaton wrote:

> On 17-Feb-2004, David Bateman <address@hidden> wrote:
>
> | According to John W. Eaton <address@hidden> (on 02/17/04):
> | > I'm not sure of the best locations for them since I don't know the
> | > typical sizes of the data.  Should they always go inside the 
> innermost
> | > loops?
> |
> | I'd rather they not go in the inner most loop. But the problem is 
> what
> | happens in a case like "a = rand(2^20,1); fft(a)" which will call
> | convert_packcomplex_1d and will only call the outer loop once, but
> | the inner one "2^20 / 2 - 1" times. So, now that I think about it, I
> | really don't know either. It depends really on what data is handed to
> | them.
> |
> | The fact is that these two routines occupy a minor proportion of the
> | time relative to the FFTW code itself. So a compromise might be to
> | just have a single call to OCTAVE_QUIT at the top of
> | convert_packcomplex_1d and convert_packcomplex_Nd.
>
> OK, I added calls to OCTAVE_QUIT at the beginning and end of each of
> these functions and in the Nd code, I also added calls to OCTAVE_QUIT
> in between each set of loops.  Perhaps that will be enough to keep
> Octave from being too sluggish to respond if an interrupt happens to
> occur while one of these functions is running.

Is it possible to fall back to a long jump for the impatient?
That is, if you press Ctrl-C twice,  can you trigger a long
jump directly from the signal?

The main reason I see why not to do it this way is
because it may leak memory, or otherwise fail to
free resources.

This would be a problem in the last case I encountered
it, which was full(sparse(5000,5000,1)), which failed
to return immediately when Ctrl-C was pressed.

It would be nice to convert Ctrl-C into a C++ exception
directly.  IIRC, the ada runtime is supposed to be able
to convert signals into exceptions, but I was never able
to find it in the gnu ada code.  Maybe they don't.

The alternative approach is radical: garbage collection.
This is not something any of us have time to consider
in a pre-2.2 release.

Paul Kienzle
address@hidden