FA-68924 / Tide and marine navigation tables / Member archive

Secondary port differences: Differences are extrapolated beyond spring and neap · case 04

Exceptional ranges produce time differences outside the published pair.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Input dict: standard port HW time hw (minutes of day), height hh, today range rng, mean spring/neap ranges sr/nr, time differences ts/tn (spring/neap, minutes) and height differences hs/hn. Interpolation factor k=(rng-nr)/(sr-nr) clamped to [0,1]; difference = neap+(spring-neap)*k. Time is wrapped to [0,1440) and rounded to whole minutes half up; height rounded to 2 decimals. Return [minutes, height].

Why this case matters

Tide tables and passage plans turn published predictions into go/no-go decisions about depth, clearance and timing.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
secondary port differences {"hw": 30, "hh": 4.9, "rng": 4.7, "sr": 4.2, "nr": 1.8, "ts": -35, "tn": 20, "hs": -0.6, "hn": -0.2}	`[1424, 4.22]`	`[1435, 4.3]`	Failed

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