[libc-commits] [PATCH] D115828: [libc] Implement correctly rounded log2f based on RLIBM library.

[Santosh Nagarakatte via Phabricator via libc-commits]

santoshn added a comment.

RLIBM's polynomial should also have 0 special case inputs and produce correctly rounded results for all inputs and for all rounding modes for log2f.

I think the current polynomial  has special case inputs because the generated polynomial is generated with a different polynomial evaluation.

Here is a revised polynomial that uses the current polynomial evaluation and produces correct results for all rounding modes and all inputs with zero violated inputs:

Polynomial: y=-3.2945312494298684154217536821552091564491707891340621650044795387657359e-16 x^(0) + 1.4426950408890866217603843324468471109867095947265625000000000000000000e+00 x^(1) + -7.2134752022691861483849606884177774190902709960937500000000000000000000e-01 x^(2) + 4.8089833027421252653610395100258756428956985473632812500000000000000000e-01 x^(3) + -3.6069225263970772221711058591608889400959014892578125000000000000000000e-01 x^(4) + 2.8949201646411226729327381690382026135921478271484375000000000000000000e-01 x^(5)


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D115828/new/

https://reviews.llvm.org/D115828