[Users] REAL_PRECISION 16

[Garrison, David]

That makes sense.  It will take me a little time to change the source code but I can try it out.  I think this is something that should be included in future versions of Cactus so extra code modifications aren’t needed.

-DG

On Jan 25, 2022, at 10:53 AM, Roland Haas <rhaas at illinois.edu<mailto:rhaas at illinois.edu>> wrote:

Hello David,

It still looks like the Vectors Thorn is required to Carpet to work.
Is there a way to not compile this Thorn and still have Carpet work?
Hmm, I have not tried this out actually.

VECTORISE=no

is an option to the vector's thorn which tells it to not use any simd
vectorization but just plain scalars. So the thorn is present, making
CarpetLib happy. But Vectors (see below) may not compile.

When using VECTORISE=no it should be possible to compile even
with CCTK_REAL being extended precision (16 bytes), though it is
possible that there are explicit checks for the CCTK_REAL width even in
that case in the code.

The good news is that, in that case only, one should be able to change
the source code to make things compile by (worst case) add a specific
sizeof(CCTK_REAL) == 16 case and using "long double" instead of
"double" for the type of variable.

Looking at the source code of Vectors one probably has to duplicate
vectors-8-default.h into vectors-16-default.h and add a branch for
CCTK_REAL_PRECISION_16 to vectors.h.

Does this explanation make sense to you and gives you an idea how you
could change the code?

Yours,
Roland

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would it?" ‹ Albert Einstein.




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