Bounded, local-only scalar reference
MXFP4 block audit lab
This lab audits one 32-value logical block. Its scale-plus-packed-byte sequence is a lab serialization, not a universal checkpoint layout. It makes no hardware, speed, energy, file-size, or model-quality claim.
Status
Ready. No data leaves this page.
Logical contract
| Element lattice | FP4 E2M1 magnitudes 0, 0.5, 1, 1.5, 2, 3, 4, 6 with both signs |
|---|---|
| Scale | one E8M0 power-of-two scale for 32 elements |
| OCP §6.3 policy | for a nonzero block, exponent = floor(log2(max absolute value / 4)); max 13 gives exponent 1 and scale 2 |
| Logical bits | 8 + 32×4 = 136; 136/32 = 4.25 bits/value |
| Input caps | exactly 32 finite values; |value| ≤ 2^120; a nonzero block maximum is ≥ 2^-125; exponent −127…127 |
| Physical boundary | lab serialization only; OCP does not prescribe one physical memory layout |
Canonical receipt
Run the audit to produce a receipt.