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neonsoftmax
confirmedC++ · NEON / Apple M4Systems & data structuresJuly 6, 2026
the question
How much does a hand-written NEON softmax over the vocabulary beat scalar libm, and at what accuracy cost?
what came out
More than 2x the scalar throughput across vocab sizes (32k-152k), at negligible cost -- relative-L2 under 1e-4 from the polynomial exp -- and consistent across vocabulary size. Standalone C++ ARM NEON; all three pre-registered predictions held.
method & receipts
- Result: confirmed
- Pre-registered — the prediction was written down and committed before the run.
- Reproducible — one script re-runs the whole thing from scratch.
- Independently reviewed — an adversarial review pass, kept in the repo.
- Machine-readable claims — every reported number, in a checkable file.
- Tested — a correctness/benchmark suite ships alongside the code.
→ read the code and re-run it
github.com/v-code01/neonsoftmax