[petsc-dev] Ugly feature of __float128

[Jeff Hammond]

Barry:

If you would only rewrite PETSc in a numerically oriented programming
language like Fortran, this problem would disappear.
See real(kind=REAL128) in ISO_FORTRAN_ENV, which is part of Fortran 2008.

Of course I am trolling, although I intend to use Fortran 2008 as my way of
getting 128b floats into MPI-4, which Jed has been asking for for a while
now.

Best,

Jeff

On Wed, Oct 28, 2015 at 9:38 PM, Jed Brown <jed at jedbrown.org> wrote:

> Barry Smith <bsmith at mcs.anl.gov> writes:
>
> >   After wasting hours debugging I just realized that gcc __float128
> >   REQUIRES that numerical constants be written with a q suffix or
> >   first they are treated as double and then converted to __float.
>
> Unsuffixed numeric literals are double.  It's the semantic of the
> language, not something they can change by adding a type.  Sorry.
>
> >    I cannot understand why this is done this way. Who wants to convert a
> code to __float128 and have to then label all floating point numbers with a
> q which of course also means the code is not compilable with other
> compilers in double.
>
> It's ugly, but you can put it in a macro:
>
> #define NUM(a)   a ## q
>



-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/
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