[Numpy-discussion] Out-of-RAM FFTs

Charles R Harris charlesr.harris@gmail....
Wed Apr 1 12:06:01 CDT 2009


On Wed, Apr 1, 2009 at 9:26 AM, David Cournapeau <
david@ar.media.kyoto-u.ac.jp> wrote:

> Greg Novak wrote:
> > 1) Numerical Recipes has an out-of-memory FFT algorithm, but looking
> > through the numpy and scipy docs and modules, I didn't find a function
> > that does the same thing.  Did I miss it?
>
> I don't think so.
>
> >  Should I get to work typing
> > it in?
> >
>
> Maybe :)
>
> > 2) I had high hopes for just memory-mapping the large array and
> > passing it to the standard fft function.  However, the memory-mapped
> > region must fit into the address space, and I don't seem to be able to
> > use more than 2 GB at a time.  So memory mapping doesn't seem to help
> > me at all.
> >
> > This last issue leads to another series of things that puzzle me.  I
> > have an iMac running OS X 10.5 with an Intel Core 2 duo processor and
> > 4 GB of memory.  As far as I've learned, the processor is 64 bit, the
> > operating system is 64 bit, so I should be able to happily memory-map
> > my entire disk if I want.  However, Python seems to run out of steam
> > when it's used 2 GB.  This is true of both 2.5 and 2.6.  What gives?
> > Is this a Python issue?
> >
>
> Yes - official python binaries are 32 bits only. I don't know how
> advanced/usable is the 64 bits build, but I am afraid you will have to
> use an unofficial build or to build it by yourself.
>
> I don't know if the following can help you:
>
>
> http://developer.apple.com/documentation/Darwin/Conceptual/64bitPorting/intro/intro.html#//apple_ref/doc/uid/TP40001064-CH205-TPXREF101
>

There was a thread about this back when...
Here<http://thread.gmane.org/gmane.comp.python.numeric.general/22353>it
is, note Michael Abshoff's directions on building 64 bit python on the
mac.

Chuck
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