[freshstart2066-create]

What

Statistical, probability, and physics shaders/guest runtimes utilize the Gauss error function and its complementary variant. While erff was previously available, erf, erfc, and erfcf were missing from libc, resulting in unresolved dynamic symbol link failures during guest initialization.

This PR implements:

• erf (erf_nid_postfix)
• erfc (erfc_nid_postfix)
• erfcf (erfcf_nid_postfix)

Implementation Details

• Backed by std::erf and std::erfc according to C99 and IEEE 754 specifications.
• Adds comprehensive unit test assertions to core/libs/tests/GuestMath.cpp validating zero signs (+0.0 vs -0.0), asymptotic limits (x -> +/-inf), standard values (x = 0.5), and quiet NaN propagation for both single and double precision variants.

Tested

• Unit tests in core/libs/tests/GuestMath.cpp (guest_math).
• Clean 3-way merge against current upstream/main with 0 conflicts (tree: d0201eff0530cb008cea33aad4de87110dc9fa58).
• python tools/check_conventions.py --base 584cc4c57: All conventions checks passed.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none
• Unblocks: PPSA01438
• GPUs tested: n/a (libc math)
• AI-assisted: yes

Co-authored-by: Nawasfadili nawasfadili@users.noreply.github.com

[github-actions]

Progress report (889cee5 → 5509b6c)

📈 System libraries: 90.25% (+0.01%, +3 implemented functions)

✅ 3 implemented

Library	Name
libc	erf_nid_postfix
libc	erfc_nid_postfix
libc	erfcf_nid_postfix

[github-actions]

Some comparisons could not be completed because a pull request conflicts with the base branch. Review these shared files manually before concluding that there is no overlap.

Pull request	Shared files not compared
PR 6044	core/libs/tests/GuestMath.cpp
PR 6414	core/libs/prx/libc/src/Math.cpp
PR 6879	core/libs/prx/libc/src/Math.cpp
PR 7201	core/libs/prx/libc/src/Math.cpp

[milescoviello]

A title that needs this: Media Player Classic PS5 1.1 (PPSA99015), new in the homebrew catalog. On main 5d9dcc4 it exits at launch:

./app.elf: symbol lookup error: ./app.elf: undefined symbol: oXgaqGVnW5o

tools/nid_names.py --nid oXgaqGVnW5o names it erf. Of the app's 329 imports, it's the only one main's libraries don't define.

The branch now conflicts with main in Math.cpp, because #5775 changed lgamma next to these lines. I resolved it by keeping main's lgamma and adding your three functions. With that, c20228eb2 merged onto 5d9dcc4 builds, and the app runs to the 120 s limit in 2 of 2 runs with pad input. In a third run with screenshots it renders its window at about 60 FPS, and its Open dialog responds to the pad.

Linux (Ubuntu 24.04, GCC 13.3, Release), RTX 4070 Ti, NVIDIA 595.99. Not checked on Windows.

AI-assisted: yes

[wachi35676]

Media Player Classic PS5 (PPSA99015, v1.1) imports erf (oXgaqGVnW5o). Setup: Windows 11, RTX 5070 Ti (NVIDIA 617.42), WinLibs GCC 15.2.0, Release. Titles are the authors' GitHub releases, unwrapped with tools/unwrap_self.py and converted with --windows. "main" is 922dc8999. For "this PR", the PR was cherry-picked onto 11acfdd84 and only the PR's own .prx was swapped into the 922dc8999 library set.

• main: fails at load in 3 of 3 runs with FAIL: unresolved ELF import oXgaqGVnW5o from libSceLibcInternal.prx.
• With this PR: 3 of 3 runs show the MPC-HC main window for 45–55 s and respond to pad input (the volume overlay shows "Volume 90%"), and guest_math passes.

Note: the branch now conflicts with main in core/libs/prx/libc/src/Math.cpp, where lgamma/signgam changed since. I tested it with main's lgamma kept and the three new functions added.

AI-assisted: yes (Claude Code); results above were run on this machine.