Complex asinh accuracy refinement #6428
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…h header disappears
davebayer
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Nov 3, 2025
libcudacxx/include/cuda/std/__complex/inverse_hyperbolic_functions.h
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libcudacxx/include/cuda/std/__complex/inverse_hyperbolic_functions.h
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libcudacxx/include/cuda/std/__complex/inverse_hyperbolic_functions.h
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miscco
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Nov 3, 2025
libcudacxx/include/cuda/std/__complex/inverse_hyperbolic_functions.h
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libcudacxx/include/cuda/std/__complex/inverse_hyperbolic_functions.h
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| // An unsafe sqrt(_Tp + _Tp) extended precision sqrt. | ||
| template <typename _Tp> | ||
| static void __device__ __host__ __forceinline__ | ||
| __internal_double_Tp_sqrt_unsafe(_Tp __hi, _Tp __lo, _Tp* __out_hi, _Tp* __out_lo) noexcept |
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Nitpick: I would strongly prefer if we would return a simple struct here instead of inout parameters
template<class _Tp>
struct _CCCL_ALIGNAS(2 * sizeof(_Tp)) __cccl_sqrt_return_hilo {
__Tp __hi;
__Tp __low;
};
Applied suggested constant initializers. Co-authored-by: Michael Schellenberger Costa <[email protected]> Co-authored-by: David Bayer <[email protected]>
…ions.h Replace __device__ __host__ Co-authored-by: Michael Schellenberger Costa <[email protected]>
…ions.h Add guards for non-cuda compilers Co-authored-by: Michael Schellenberger Costa <[email protected]>
…ions.h undo-ing clang-format Co-authored-by: David Bayer <[email protected]>
davebayer
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Nov 3, 2025
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| #include <cuda/std/__cmath/abs.h> | ||
| #include <cuda/std/__cmath/copysign.h> | ||
| #include <cuda/std/__cmath/isinf.h> | ||
| #include <cuda/std/__cmath/isnan.h> | ||
| #include <cuda/std/__cmath/trigonometric_functions.h> | ||
| #include <cuda/std/__complex/complex.h> | ||
| #include <cuda/std/__complex/exponential_functions.h> | ||
| #include <cuda/std/__complex/logarithms.h> | ||
| #include <cuda/std/__complex/nvbf16.h> | ||
| #include <cuda/std/__complex/nvfp16.h> | ||
| #include <cuda/std/__complex/roots.h> | ||
| #include <cuda/std/limits> | ||
| #include <cuda/std/numbers> |
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Why are all of these includes dropped?
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My prejudice basically, in math we get compile time build bugs because of header parsing so I usually try take them out if they're not needed. I was over zealous here it seems, not sure why this even built on my machine. Added them back, like I would probably have to do later after changing the other functions also.
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/ok to test 9629a78 |
😬 CI Workflow Results🟥 Finished in 2h 13m: Pass: 80%/90 | Total: 1d 06h | Max: 1h 32m | Hits: 94%/152135See results here. |
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Update the complex asinh function to avoid numerical issues.
The current complex asinh function loses accuracy in several places.
These mostly relate to over/underflow, and catastrophic cancellation for tough values.
This new version fixes these accuracy issues while retaining it's perf.
Perf
On GH100 we don't have much perf difference. (There used to be a much large perf gap until #5371 got merged, which the current version is availing of).
Using the math-teams standard math_bench test we have the following:
Operations/SM/cycle:
casinh():Correctness
The current version has several intervals where accuracy gets lost.
Apart from the usual over/underflow suspects, there is also some very subtle intervals where accuracy gets badly thrown out, especially by catastrophic cancellation very close to
+-i.This new version fixes these and testing gives the following:
GPU Correctness
For the new version, an intensive bracket and bisect search, along with testing special hard values, gives:
CPU Correctness