FA-72098 / Error-correcting codes / Member archive

Min-sum magnitude includes the edge own message · case 03

The least reliable edge receives its own small magnitude back.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Offset min-sum check-node update for LDPC decoding with integer LLRs. For each edge i the outgoing message is the product of the signs of all OTHER incoming LLRs (0 counts as positive) times max(min |other LLR| - beta, 0). Fewer than two edges returns None. Return the outgoing messages in edge order.

Why this case matters

LDPC decoders in Wi-Fi, 5G and SSD controllers run this update billions of times per second.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression [[6, -11, 10, -5, 2, 8], 1]	`[1, -1, 1, -1, 1, 1]`	`[1, -1, 1, -1, 4, 1]`	Failed

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