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From: "g.peterhoff@t-online.de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/77776] C++17 std::hypot implementation is poor
Date: Tue, 19 Mar 2024 00:09:03 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D77776

--- Comment #23 from g.peterhoff@t-online.de ---
Hello Matthias,
you've given me new ideas. I think we agree on implementing hypot3 using a
scaling factor. But the correct value is not yet implemented here either; do
you have a suggestion?
A version here: https://godbolt.org/z/Gd53cG9YG
I've intentionally broken hypot_gp into small pieces so that you can play
around with it. This is of course unnecessary for a final version.

General
* The function must of course work efficiently with all FP types.

Questions
* Sorting: It is theoretically sufficient to sort the values x,y,z only to =
the
extent that the condition x,y <=3D z is fulfilled (HYPOT_SORT_FULL).
* Accuracy: This is better with fma (HYPOT_FMA).
* How do you create the benchmarks? I could do this myself without getting =
on
your nerves.

thx
Gero=