On 9 March 2011 20:53, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
> On Mar 9, 2011, at 4:54 PM, Lisandro Dalcin wrote:
>
>> Barry, what's the status of this?:
>> http://lists.mcs.anl.gov/pipermail/petsc-dev/2005-November/000086.html
>>
>> I configured with --download-c-blas-lapack, but it seems that the
>> argument is plain ignored, configure.log does not provide any clue
>> about what's going on, configure success, BLAS/LAPACK config vars are
>> plain empty, PETSc builds fine, but at make test I get linker errors
>> about missing BLAS symbols... BTW, I've manually downloaded f2c
>> blas-lapack tarball, but I cannot figure out how you managed to get a
>> "long double" build...
>
> ? Unfortunately Satish threw away that tarball of cblas/lapack and replaced 
> it with one generated by the lapack boys which cannot build with long double.
>
>>
>> Do you really got it working?
>
> ? Yes but it won't work anymore.
>
> ? To top it off long double in gcc uses 128 bits but actually only uses the 
> 80 bit floating point units so it is not worth it. Plus the MPICH long double 
> operations like MPI_SUM didn't work properly.
>
> ? But, Jed pointed out that gcc has a new way of doing 128 bit floating 
> point. You may see some pushes into PETSc-dev in the next few days as I try 
> to get it working. Keep your eyes open.
>

Are you talking about __float128 ?


> ? Barry
>
> ?BTW: this is most definitely a petsc-dev question and not a personal 
> question to me.
>

I agree now :-). I thought I must be missing something obvious, and I
didn't want to make noise.

Many thanks for your clarifications...


-- 
Lisandro Dalcin
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