mxfloor

the question

Does MX block floating-point's single shared E8M0 floor-scale both silence small neighbors and clip the block max, and do the two laws meet on the largest element?

what came out

An element rounds to zero when |v|/M < 2^(e_n-e_x-m-1)/phi; in MXFP4 any element 16-32x below the block max is annihilated (measured 6.8-10.4% silenced, FP8 0.0%). The floor scale clips the block max when phi>top_mantissa, up to 25% for FP4 and 12.5% for FP8. The block max both silences neighbors and is itself worst-quantized.

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