FA-69873 / Map projection transforms / Member archive

Spherical web mercator inverse projection: exponent sign · case 03

Latitudes come back with the wrong hemisphere.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input [x, y] metres (sphere radius 6378137). Eastings outside the world extent E = 20037508.342789244 are wrapped into [-E, E) first. Return [lon, lat] in degrees rounded to 7 decimals.

Why this case matters

Converting clicked map positions or tile corners back to geographic coordinates uses this inverse; faults misplace every reverse-geocoded point.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
control #4	`[9.9999999, -10.0]`	`[9.9999999, 10.0]`	Failed

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