Re: [Discuss-gnuradio] FFTW Problems

[Bob McGwier]

Eric Blossom wrote:

> On Thu, Sep 21, 2006 at 05:51:31PM -0500, Ron Shaffer wrote:
>  
>
> > I'm trying to build with the latest svn source as of this past weekend 
> > in FC 4.  below is a snip of my configure and make outputs
> > ... Can someone help me with this please - I'm getting unresolved 
> > externals on FFTW -
> > ..Ron
> >    
>
> You don't have a version of FFTW installed that includes the single
> precision versions.
>
> The easiest way to fix it is to build fftw from source as described in
> the README at the top of the gnuradio tree.
>
>    (3)  FFTW 3.0 or later             http://www.fftw.org
>
>    IMPORTANT!!!  When building FFTW, you MUST use the --enable-single and
>    --enable-shared configure options.  This builds the single precision
>    floating point version which we use.  You should also use either the
>    --enable-3dnow or --enable-sse options if you're on an Athlon or Pentium
>    respectively.
>  
The latter bits have a large impact on the speed so be sure and enable 
the simd instruction codelets in FFTW.  In fact,  you can enable BOTH, 
and FFTW will just do the right thing.  I never trust that the default 
included packages in the distro's have these flags turned on during the 
compile.  I always replace FFTW with my own compile from source in self 
defense.

> Eric
>
>
>  


--
Robert W. McGwier, Ph.D.
Center for Communications Research
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