Add gamma function to f32 and f64 #99747

ankane · 2022-07-26T05:19:05Z

Adds the gamma function to f32 and f64 (tgamma and tgammaf from C).

Refs:

rust-highfive · 2022-07-26T05:19:08Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @m-ou-se (or someone else) soon.

Please see the contribution instructions for more information.

rustbot · 2022-07-26T05:19:08Z

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

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Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
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Changing observable runtime behavior of library APIs

joshtriplett · 2022-07-28T06:26:40Z

LGTM. Please file a tracking issue, then r=me.

ankane · 2022-07-28T07:26:10Z

Thanks @joshtriplett, tracking issue added.

joshtriplett · 2022-07-28T07:57:28Z

@bors r+ rollup

bors · 2022-07-28T07:57:30Z

📌 Commit 7d2e763 has been approved by joshtriplett

It is now in the queue for this repository.

Add gamma function to f32 and f64 Adds the [gamma function](https://en.wikipedia.org/wiki/Gamma_function) to `f32` and `f64` (`tgamma` and `tgammaf` from C). Refs: - rust-lang/rfcs#864 - rust-lang#18271

Dylan-DPC · 2022-07-28T10:57:31Z

failed in rollup

Dylan-DPC · 2022-07-28T10:57:37Z

@bors r-

raoulstrackx · 2022-07-28T13:15:31Z

library/std/src/f32/tests.rs

@@ -550,6 +550,21 @@ fn test_atanh() {
    assert_approx_eq!((-0.5f32).atanh(), -0.54930614433405484569762261846126285f32);
 }

+#[test]
+fn test_gamma() {
+    assert_eq!(0.0f32.gamma(), f32::INFINITY);


This test causes compile time errors on platforms like x86_64-fortanix-unknown-sgx and probably others:

12:04:56 = note: rust-lld: error: undefined symbol: tgammaf 12:04:56 >>> referenced by std.143fe29c-cgu.2 12:04:56 >>> /home/jenkins/workspace/rust-sgx-ci/rust/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-fortanix-unknown-sgx/release/deps/std-e08c880d8c834560.std.143fe29c-cgu.2.rcgu.o:(std::f32::tests::test_gamma::he9b80e8a0cc72b6a) 12:04:56 >>> referenced by std.143fe29c-cgu.2 12:04:56 >>> /home/jenkins/workspace/rust-sgx-ci/rust/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-fortanix-unknown-sgx/release/deps/std-e08c880d8c834560.std.143fe29c-cgu.2.rcgu.o:(std::f32::tests::test_gamma::he9b80e8a0cc72b6a) 12:04:56 >>> referenced by std.143fe29c-cgu.2 12:04:56 >>> /home/jenkins/workspace/rust-sgx-ci/rust/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-fortanix-unknown-sgx/release/deps/std-e08c880d8c834560.std.143fe29c-cgu.2.rcgu.o:(std::f32::tests::test_gamma::he9b80e8a0cc72b6a) 12:04:56 >>> referenced 6 more times 12:04:56 12:04:56 rust-lld: error: undefined symbol: tgamma 12:04:56 >>> referenced by std.143fe29c-cgu.3 12:04:56 >>> /home/jenkins/workspace/rust-sgx-ci/rust/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-fortanix-unknown-sgx/release/deps/std-e08c880d8c834560.std.143fe29c-cgu.3.rcgu.o:(std::f64::tests::test_gamma::hff115a05914e5bdc) 12:04:56 >>> referenced by std.143fe29c-cgu.3 12:04:56 >>> /home/jenkins/workspace/rust-sgx-ci/rust/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-fortanix-unknown-sgx/release/deps/std-e08c880d8c834560.std.143fe29c-cgu.3.rcgu.o:(std::f64::tests::test_gamma::hff115a05914e5bdc) 12:04:56 >>> referenced by std.143fe29c-cgu.3 12:04:56 >>> /home/jenkins/workspace/rust-sgx-ci/rust/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-fortanix-unknown-sgx/release/deps/std-e08c880d8c834560.std.143fe29c-cgu.3.rcgu.o:(std::f64::tests::test_gamma::hff115a05914e5bdc) 12:04:56 >>> referenced 6 more times 12:04:56 12:04:56 12:04:56 error: could not compile `std` due to previous error

Looking into it, these tgamma and tgammaf symbols exists, but are not exported from the compiler-builtins crate. These should probably be added here.

Thanks @raoulstrackx! Submitted a PR there: rust-lang/compiler-builtins#482

Great! Thanks @ankane !

raoulstrackx · 2022-07-28T13:15:59Z

library/std/src/f64/tests.rs

@@ -535,6 +535,21 @@ fn test_atanh() {
    assert_approx_eq!((-0.5f64).atanh(), -0.54930614433405484569762261846126285f64);
 }

+#[test]
+fn test_gamma() {
+    assert_eq!(0.0f64.gamma(), f64::INFINITY);


Causes similar issues as above

mati865 · 2022-07-29T07:48:04Z

I think this PR should never be rolled up because it's going to fail on more targets like *-windows-gnu (only non llvm ABI) as MSVCRT doesn't provide these symbols.

@bors rollup=never

bors · 2022-07-29T07:48:06Z

@mati865: 🔑 Insufficient privileges: not in try users

Dylan-DPC · 2022-07-29T08:48:26Z

@bors rollup=never

joshtriplett · 2022-07-29T16:09:15Z

@mati865 I was expecting that these symbols were being provided by compiler-builtins fallbacks on all platforms. We do need fallbacks for platforms that don't have these.

mati865 · 2022-07-29T16:22:12Z

@joshtriplett I'm away until next week but mingw-w64 seems to provide own implementation when using MSVCRT but it returns wrong results for certain values. This issue has been fixed 3 years ago but Rust uses 5 years old release.
I hope to open PR with bump next week but merging it may take some time so feel free to search for workarounds (even more extreme ones like disabling those unit tests for windows-gnu).

ankane · 2022-07-30T01:10:26Z

Just bumped compiler_builtins with the exported symbols.

bors · 2022-08-13T08:00:59Z

☔ The latest upstream changes (presumably #100380) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2023-07-31T20:46:15Z

⌛ Testing commit 793e952d9beb8ed40ecbfa188e37882dfdb15555 with merge ee51e45123e931937c445a123b67d24d3e3cd4fa...

bors · 2023-07-31T21:47:53Z

💔 Test failed - checks-actions

workingjubilee · 2023-07-31T21:49:11Z

r? @workingjubilee
@rustbot author

ankane · 2023-08-07T23:39:05Z

Bumped compiler_builtins

@rustbot ready

workingjubilee · 2023-08-08T22:27:14Z

I hope we can solve the underlying problem there, soon. ( And that it doesn't crop up again for this PR... )

@bors r+

bors · 2023-08-08T22:27:16Z

📌 Commit a75e228 has been approved by workingjubilee

It is now in the queue for this repository.

bors · 2023-08-09T03:14:35Z

⌛ Testing commit a75e228 with merge 8838c73...

bors · 2023-08-09T05:50:05Z

☀️ Test successful - checks-actions
Approved by: workingjubilee
Pushing 8838c73 to master...

ankane · 2023-08-09T06:03:10Z

Thanks everyone for helping with this!

rust-timer · 2023-08-09T10:36:00Z

Finished benchmarking commit (8838c73): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.4%, 0.4%]	1
Regressions ❌ (secondary)	0.6%	[0.6%, 0.6%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.1%	[-1.8%, -0.3%]	2
All ❌✅ (primary)	0.4%	[0.4%, 0.4%]	1

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.4%	[-2.4%, -2.4%]	1
All ❌✅ (primary)	-	-	0

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 633.338s -> 632.915s (-0.07%)

RalfJung · 2023-08-11T05:50:13Z

library/std/src/f32.rs

+        unsafe { cmath::tgammaf(self) }
+    }
+
+    /// Returns the natural logarithm of the gamma function.


This is wrong, it returns the natural log of the absolute value of the gamma function.

#[test] fn test_ln_gamma() { assert_approx_eq!(1.0f64.ln_gamma().0, 0.0f64); assert_eq!(1.0f64.ln_gamma().1, 1); assert_approx_eq!(2.0f64.ln_gamma().0, 0.0f64); assert_eq!(2.0f64.ln_gamma().1, 1); assert_approx_eq!(3.0f64.ln_gamma().0, 2.0f64.ln()); assert_eq!(3.0f64.ln_gamma().1, 1); assert_approx_eq!((-0.5f64).ln_gamma().0, (2.0 * consts::PI.sqrt()).ln()); assert_eq!((-0.5f64).ln_gamma().1, -1); }

? am I just missing something, if so why does the final test case pass...

Γ(-0.5f64) is negative, its natural log should be undefined

...well, it sounds obvious now that you've said it, so...!
#114754

rust-highfive assigned m-ou-se Jul 26, 2022

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ankane mentioned this pull request Jul 28, 2022

Tracking Issue for float_gamma #99842

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Dylan-DPC mentioned this pull request Jul 28, 2022

Rollup of 5 pull requests #99847

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raoulstrackx reviewed Jul 28, 2022

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ankane mentioned this pull request Jul 28, 2022

Add tgamma and tgammaf rust-lang/compiler-builtins#482

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ankane force-pushed the float_gamma branch from eb0999e to 943b550 Compare August 21, 2022 19:27

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ankane mentioned this pull request Jul 31, 2023

Add lgamma_r and lgammaf_r to MinGW rust-lang/compiler-builtins#546

Merged

Bump compiler_builtins to 0.1.100

a75e228

ankane force-pushed the float_gamma branch from 793e952 to a75e228 Compare August 7, 2023 23:38

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bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 9, 2023

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avhz mentioned this pull request Mar 12, 2024

Add error functions (erf, erfc) to the f32/f64 API. rust-lang/libs-team#352

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Add gamma function to f32 and f64 #99747

Add gamma function to f32 and f64 #99747

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Overall result: ❌✅ regressions and improvements - no action needed

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