FA-71217 / Weather index computation / Member archive

Antecedent precipitation index: multi-day gap decay · case 02

After a week without reports the index has barely decayed.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

obs are [day, precip_mm] in any order; process in ascending day order (stable for equal days). Between observations API decays by k^(day gap); several reports on the same day accumulate without decay; negative precipitation is a sensor glitch treated as 0. Return API after each observation, rounded to 0.01.

Why this case matters

Flash-flood guidance and soil wetness models use API as a moisture state.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
basin 4	`[30.0, 38.0, 62.3, 65.45, 68.14, 70.42, 64.85]`	`[30.0, 42.5, 60.71, 73.21, 85.71, 98.21, 88.48]`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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