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Update behavior-math-clamp-nan.md

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Arseny Kapoulkine 2023-07-30 20:20:05 -07:00 • committed by GitHub
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rfcs/behavior-math-clamp-nan.md
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@ -31,7 +31,7 @@ This can be a problem if:
As a consequence of this change, `math.clamp` return value `r` will always satisfy `a <= r <= b`.
Note that if the input or one of the limits is a negative zero we will not guarantee that the sign of the output is preserved; positive and negative zeros are considered equal under this proposal.
The behavior of NaN clamping outside of Luau varies. Shading languages (HLSL, GLSL in Vulkan, MSL in Metal) typically guarantee that `clamp(t, a, b)` is equal to a when t is NaN; C++ `std::clamp` provides no guarantees and in fact treats NaN as a technically-invalid input; C#, Rust and Julia preserve NaN; Zig returns the upper limit. Despite the differences, we believe that for Luau domain guaranteeing that the result is in the specified range is more valuable than preserving NaN, and returning the lower limit is more consistent with industry practice than returning upper limit.
The behavior of NaN clamping outside of Luau varies. Shading languages (HLSL, GLSL in Vulkan, MSL in Metal) typically guarantee that `clamp(t, a, b)` is equal to a when t is NaN; C++ `std::clamp` provides no guarantees and in fact treats NaN as a technically-invalid input; C#, Rust and Julia preserve NaN; Zig returns the upper limit. Ruby raises an error when input is NaN. Swift does not implement clamping for floats. Despite the differences, we believe that for Luau domain guaranteeing that the result is in the specified range is more valuable than preserving NaN, and returning the lower limit is more consistent with industry practice than returning upper limit.
> The following text is non-normative as it relates to the specific implementation consequences.