FA-91409 / Digital signal filters / Member archive

Running average divides warm-up sums by the full window · case 04

The first W-1 outputs are biased toward zero.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Input [W, samples]; causal moving average using a running sum. During warm-up divide by the number of samples seen (min(n+1, W)). Return exact fraction strings; "bad-window" if W < 1.

Why this case matters

Running-sum boxcars are the cheapest smoothing filter; eviction and warm-up slips bias every early or late sample.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: random average 11	`["-1/5", "2/5", "1"]`	`["-1", "1", "5/3"]`	Failed

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