Crate feral_amf 

Approximate Minimum Fill (AMF / HAMF4) fill-reducing ordering.

Standalone clean-room implementation of the AMF quotient-graph algorithm (Amestoy 1999 habilitation thesis, MUMPS HAMF4 variant). The metric is approximate fill rather than approximate degree — the per-variable score is

RMF(i) = ( deg(i) * (deg(i) - 1 + 2*degme) - WF(i) ) / (nv(i) + 1)

quantized into a 2N + 2 head-array with a coarse stride above N. The inner loop, including the lazy WF(e) element cache, the supervariable max-merge of WF, and the saturated/regular RMF branch, lives in feral-ordering-core behind the MinFill Metric impl.

The public surface conforms to the FERAL ordering-crate contract (dev/plans/ordering-crate-contract.md). CscPattern, OrderingStats, OrderingError, and CONTRACT_VERSION are re-exported from feral-ordering-core.

HAMF4 always aggressively absorbs elements, so AmfOptions does not expose an aggressive knob; the dense_alpha knob lives in the shared workspace and behaves identically to feral-amd’s.

Structs

AmfOptions

Tunable parameters for AMF ordering.

AmfStats

Diagnostic counters collected during AMF ordering.

CscPattern

Borrowed symmetric sparsity pattern in CSC form.

OrderingStats

Diagnostic counters shared by every ordering producer.

Enums

OrderingError

Shared error shape for the ordering-crate contract.

Constants

CONTRACT_VERSION

Version of the shared ordering-crate contract.

Functions

amf_order

Compute a fill-reducing AMF ordering.

amf_order_full

Contract-conforming ordering producer.

amf_order_opts

Compute an AMF ordering with explicit options.

amf_order_with_stats

Compute an AMF ordering and return the crate-specific diagnostic counters.