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| author | lntue <35648136+lntue@users.noreply.github.com> | 2024-07-03 18:05:24 -0400 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-07-03 18:05:24 -0400 |
| commit | 7d68d9d2f27535e03934383220282e18edd0c1e8 (patch) | |
| tree | 7a362f7e21a8a266616da1379b3d6f88faad5ee1 /mlir/lib/Bytecode/Reader/BytecodeReader.cpp | |
| parent | 5828b04b0373f10fade7eefbeb181dc8ceb98422 (diff) | |
| download | llvm-7d68d9d2f27535e03934383220282e18edd0c1e8.zip llvm-7d68d9d2f27535e03934383220282e18edd0c1e8.tar.gz llvm-7d68d9d2f27535e03934383220282e18edd0c1e8.tar.bz2 | |
[libc][math] Implement correctly rounded double precision tan (#97489)
Using the same range reduction as `sin`, `cos`, and `sincos`:
1) Reducing `x = k*pi/128 + u`, with `|u| <= pi/256`, and `u` is in
double-double.
2) Approximate `tan(u)` using degree-9 Taylor polynomial.
3) Compute
```
tan(x) ~ (sin(k*pi/128) + tan(u) * cos(k*pi/128)) / (cos(k*pi/128) - tan(u) * sin(k*pi/128))
```
using the fast double-double division algorithm in [the CORE-MATH
project](https://gitlab.inria.fr/core-math/core-math/-/blob/master/src/binary64/tan/tan.c#L1855).
4) Perform relative-error Ziv's accuracy test
5) If the accuracy tests failed, we redo the computations using 128-bit
precision `DyadicFloat`.
Fixes https://github.com/llvm/llvm-project/issues/96930
Diffstat (limited to 'mlir/lib/Bytecode/Reader/BytecodeReader.cpp')
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