PAC-MAN Benchmark (Linear Acoustics 4): Reference CSV Audit and Corrected High-Precision Modal Reference

Audit of the reference CSV files distributed with the PAC-MAN benchmark (Linear Acoustics 4, Ziegelwanger & Reiter; Zenodo record 8419907), together with a corrected reference solution and everything needed to reproduce it. The audit identifies three defects in the original CSVs: (1) the pressure row at φ = 355° duplicates the row at φ = 0° in all four source cases; (2) surface-vibration symmetry pairs give φ(a) + φ(b) = 355° instead of 360°; (3) an angular drift in the lower-half receiver angles. The pattern is consistent with the receivers having been evaluated on an endpoint-inclusive grid θⱼ = 360°·j/71 rather than the documented φ = 0°, 5°, …, 355°. Direct modal evaluation on that grid reproduces the original files to a relative L2 error of at most 1.03 × 10⁻³. The corrected reference was regenerated from the analytical modal solution of Ziegelwanger & Reiter (2017), using mpmath at 50 digits with 200 modal terms, at r = 2 m and φ = 0°, 5°, …, 355°, for all four source cases (plane wave, line source, disk source, surface vibration) at 16 Hz to 4 kHz. The CSVs reproduce bit for bit from the included generator. Contents: the original Zenodo CSVs (for comparison), the corrected mpmath CSVs, the generator, the audit scripts and their saved outputs, figures, an independent validation with a 2D Rust BEM solver, and the report (pacman_bem_reference_audit.pdf). SHA256SUMS lists checksums for every file.