A Nonzero Derivative Becomes Zero | MLX expm1 Audit

An independent, reproducible numerical audit of Apple MLX 0.32.2 on CPU. The report separates the VJP defect from the already public float64-exp issue #3047 and includes four native control variants.

Full report: https://www.gero.uz/research/articles/mlx-expm1-tail-vjp.html
Code, tests and patch: https://github.com/kadyrbekovhamit-cyber/gero-numerical-observatory/tree/main/audits/2026-09-10-mlx-expm1-tail-vjp/
Known dependency: https://github.com/ml-explore/mlx/issues/3047
Analogous JAX report (credited, not rerun): https://github.com/jax-ml/jax/issues/39794

Scope: CPU float32/float64; isolated native translation-unit rebuild. No full current-main rebuild, GPU validation, performance qualification, model-level impact or upstream acceptance is claimed.

Narration uses a synthetic voice (macOS Samantha; fictional narrator Alex Vector). Original diagrams. AI-assisted research, code, writing and production; editorial review by Technology Product / Xamit Kadirbekov.

#MLX #Autodiff #NumericalComputing