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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /vendor/compiler_builtins/libm/src/math/atanhf.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/compiler_builtins/libm/src/math/atanhf.rs')
-rw-r--r-- | vendor/compiler_builtins/libm/src/math/atanhf.rs | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/vendor/compiler_builtins/libm/src/math/atanhf.rs b/vendor/compiler_builtins/libm/src/math/atanhf.rs new file mode 100644 index 000000000..7b2f34d97 --- /dev/null +++ b/vendor/compiler_builtins/libm/src/math/atanhf.rs @@ -0,0 +1,36 @@ +use super::log1pf; + +/* atanh(x) = log((1+x)/(1-x))/2 = log1p(2x/(1-x))/2 ~= x + x^3/3 + o(x^5) */ +/// Inverse hyperbolic tangent (f32) +/// +/// Calculates the inverse hyperbolic tangent of `x`. +/// Is defined as `log((1+x)/(1-x))/2 = log1p(2x/(1-x))/2`. +pub fn atanhf(mut x: f32) -> f32 { + let mut u = x.to_bits(); + let sign = (u >> 31) != 0; + + /* |x| */ + u &= 0x7fffffff; + x = f32::from_bits(u); + + if u < 0x3f800000 - (1 << 23) { + if u < 0x3f800000 - (32 << 23) { + /* handle underflow */ + if u < (1 << 23) { + force_eval!((x * x) as f32); + } + } else { + /* |x| < 0.5, up to 1.7ulp error */ + x = 0.5 * log1pf(2.0 * x + 2.0 * x * x / (1.0 - x)); + } + } else { + /* avoid overflow */ + x = 0.5 * log1pf(2.0 * (x / (1.0 - x))); + } + + if sign { + -x + } else { + x + } +} |