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

[Daniel J Sebald]

David Bateman wrote:

> According to Daniel J Sebald <address@hidden> (on 02/16/04):
>  
>
> > Any ramifications of fft_wisdom not being correct on server environments?
> >
> > Do the fft_wisdom functions remove the existing wisdom files at the very 
> > end of the trial and error process?  Otherwise mistakingly running the 
> > command could lead to anguish.
> >    
>
> This is a difficult issue. The way I treated it was
>
> 1) The system wisdom file (usually in /etc/fftw/wisdom) is imported at 
>   startup. Hopefully, the user won't install an incorrect wisdom file 
>   here. 
> 2) The fft_wisdom command can import or export wisdom files. These can
>   be used to override the system wisdom if needed
> 3) There is a flag to 'fft_wisdom' that forces it to overwrite a wisdom 
>   file even if it exists.
> 4) Furthemore, if 'fft_wisdom([257 257])' for example is called, the process
>   is to create an octave temporary file in $(TMPDIR)/oct-*. Invoke with
>   'system' the command 'fftw-wisdom -n -o $(TMPDIR)/oct-*'. The '-n' forces
>   the process to not use the system wisdom, so that bad wisdom can also
>   be overridden in this manner. The temporrary file is deleted when octave
>   exits and so won't be reused.
>
> There are still ways the user can import bad wisdom, for instance calling
> fft_wisdom('file') thinking that 'file' doesn't exist, when it does and
> contains wisdom for anotehr platform. Do you think it is worth splitting
> fft_wisdom into three commands? fft_save_wisdom, fft_load_wisdom and 
> fft_create_wisdom?

No, probably not.  It is common for the meaning of an Octave function to 
be dependent upon the type of variable passed into it, or not passed in.

fft_wisdom('mywisdom.wis');
would set up Octave to use a wisdom file other than the default, fine.

fft_wisdom();
fft_wisdom()  -- prints the contents of the wisdom file?
would run wisdom and overwrite the default file.  Maybe this is a bit dodgy.

save 'mywisdom.wis' fft_wisdom();
I'm not sure about the saving portion of it.

Dan