FA-68909 / Tide and marine navigation tables / Member archive

Cosine curve time for height: Hours are rounded before conversion to minutes · case 04

Times are always reported on the whole hour.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Input [t1,h1,t2,h2,h] (hours, metres) for consecutive turning points with t2>t1 and h1!=h2. Height follows h1+(h2-h1)*(1-cos(pi*s/T))/2 with s elapsed and T=t2-t1. Return the time in whole minutes (rounded half up) when the height h is first reached on that half-cycle, or None when h lies outside the closed range of h1..h2.

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
cosine curve time for height [0, 0.6, 6.2, 4.4, 4.4]	`360`	`372`	Failed

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