Experiment: VFPU 46-Input Transcendental Corpus
Experiment ID: EXP-VFPU-TRANSCEND-20260805-A · State: ACCEPTANCE ELIGIBLE · Classification: source-owned real-hardware measurement
Question
Which outputs from eight VFPU transcendental/helper operations agree with a real PSP across a deliberately shared 46-input raw-float corpus?
Fixture and environment
Source-owned 46-input IEEE-754 bit-pattern corpus; exact probe/capture is private, while the normalized digests below are public-safe. Hardware: PSP-3001, 6.61-ARK, PSPLink-qualified session. Repeat count: one accepted corpus capture with software controls; independent same-model replication remains wanted.
Procedure
Feed the identical 46 raw bit patterns to vrcp, vrsq, vsqrt, vasin, vlog2, vsin, vcos, and vexp2. Hash each operation’s raw output vector with FNV-1a. Compare PSP output with current Nakagawa and a local PPSSPP build, keeping interpreter/JIT paths separate.
Public-safe observation
| Operation | PSP/Nakagawa digest | Tested PPSSPP relation |
|---|---|---|
vrcp |
0xe1ec308a |
interpreter matched; JIT differed in that build |
vrsq |
0x657aaf94 |
diverged in tested paths |
vsqrt |
0x0e1bce1b |
diverged in tested paths |
vasin |
0x7e39e3d2 |
matched |
vlog2 |
0x8bff5b53 |
diverged in tested paths |
vsin |
0x0235f855 |
matched |
vcos |
0x2e4b69bd |
diverged in tested paths |
vexp2 |
0x6558a646 |
diverged in tested paths |
For input 0x00000001, the same campaign recorded PSP vsqrt → 0x00000000 and vrsq → 0x7f800000; see FIND-VFPU-DENORM-001.
Interpretation
Real PSP hardware selected Nakagawa’s output for all eight operations over this exact corpus. The result exposes a hardware/software differential and a concrete denormal edge, not exhaustive correctness.
Claims not supported
- No all-input or all-VFPU proof.
- No universal PPSSPP bug claim: the archived build configuration must be reproduced before assigning a release-level defect.
- No independent replication: Nakagawa and PPSSPP agreement is common-mode evidence when lineage or tables overlap.
Implementation and prior art
Compare the current public helpers in src/rt/recomp.c and the public synthesis VFPU Transcendentals and Denormals. Prior-art survey targets PSPAutotests, PSP Developer Wiki/DavidGF VFPU documentation, PPSSPP release source/issues, and historical PSP test archives.
Replication
Rebuild the source-owned corpus with a pinned toolchain, then run the same 46 inputs on PSP-1000/2000 and a second PSP-3000. Report only raw operation digests and selected input/output rows, plus model/firmware/CFW and repeat count. Do not upload private captures or commercial content.
Related: FIND-VFPU-TRANSCEND-001 · FIND-VFPU-DENORM-001 · CONFLICT-REAL-HARDWARE-AUTHORITY-001 · VFPU register-addressing finding.
Publication safety: public normalized digests only; exact private fixture withheld. Last reviewed: 2026-08-11.