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Re: ITP: fftw-3.0.1


--- Yaakov S  wrote:

> Gentoo[1] uses an interesting technique to build both single- and
> double-precision libraries (the single-precision libs have an additional
> 'f' in their name) from the same package.
> 
> This could be adapted for our purposes (yes, I've actually done it):
> 
> In the configure stage:
> mkdir -p ${objdir}/single
> cd ${objdir}/single
> [run configure with --enable-float]
> mkdir -p ${objdir}/double
> cd ${objdir}/double
> [run default configure]
> 
> In the make/install/clean/check stages:
> cd ${objdir}/single && make {,clean,check,install DESTDIR=${instdir}}
> cd ${objdir}/double && make {,clean,check,install DESTDIR=${instdir}}
> 
> Hope this helps.
> 
> [1]
>
http://www.gentoo.org/cgi-bin/viewcvs.cgi/sci-libs/fftw/fftw-3.0.1-r2.ebuild?view=markup
> 
> 
> Yaakov

This is fine, and I appreciate the suggestion, but I need to hear that someone
actually _wants_ to use single precision before I provide such a library.

IMO, single precision is generally anachronistic on today's hardware.  Back in
the stone age ('70's), computers actually had separate single and double
precision floating point units, and double precision actually took longer to
execute.  Today's hardware excecutes everything in 80 bit precision, and single
precision means it just truncates the result for storage.  Well, how many
people today are pushing their memory or storage boundaries to the point where
they want to throw away some precision to save some space?  Not many, I'll bet.

But again, thanks for the suggestion.

Jim Phillips


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