FA-69065 / Tide and marine navigation tables / Member archive

High and low water extraction: Plateau midpoint is floored to a whole sample · case 05

Even-length stands are timed half an interval early.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Input [h, dt, minr]: equally spaced heights every dt minutes. Interior extrema (plateaus collapse to their midpoint time) are candidates; series endpoints never are. A candidate of the same type as the last accepted event replaces it only if more extreme; otherwise a candidate whose height differs from the last accepted event by less than minr is ignored. Return [[type, 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
high and low water extraction [[4.0, 5.0, 5.0, 5.0, 5.0, 4.0, 1.0, 1.0, 2.0], 15, 0.5]	`[["HW", 37.5, 5.0], ["LW", 90, 1.0]]`	`[["HW", 37.5, 5.0], ["LW", 97.5, 1.0]]`	Failed

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