FA-54915 / Astronomical coordinate conventions / Member archive

Spectral axis reversal: Reversed dispersion retains its original orientation · case 05

The adapter reports an incorrect increment while other fields remain valid.

Member previewVariant 5 · 3 implementations · 6 checks per implementation

Case contract

Reverse a finite spectral pixel axis of length L using one-based pixel labels. Reference pixel, edge pixel coordinates, dispersion coefficients, and velocity-increment metadata must describe the same physical samples. Quadratic coefficient is unchanged under reversal about the reference. Output fields are defined by: reference = d['L']+1-d['r']; pixel = d['L']+1-d['p']; increment = -d['step']; quadratic = d['q']; velocity_increment = -d['vel']; interval = [d['L']+1-d['hi'],d['L']+1-d['lo']]

Why this case matters

Catalog, detector, sky-coordinate, and spectroscopy adapters must preserve the association between numeric coordinates and their declared reference conventions.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
astronomical fixture 0	`{"increment": 2, "interval": [12, 19], "pixel": 18, "quadratic": 3, "reference": 11, "velocity_increment": -5}`	`{"increment": -2, "interval": [12, 19], "pixel": 18, "quadratic": 3, "reference": 11, "velocity_increment": -5}`	Failed

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

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