FA-69349 / Orbital propagation / Member archive

Elliptic Kepler solver: Mean anomaly is not reduced to one revolution · case 04

Multi-revolution or negative mean anomalies return eccentric anomalies outside [0,2pi).

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Input [M, e] (radians). Return None unless 0<=e<1. Reduce M into [0,2pi), start Newton at M (e<0.8) or pi, iterate E -= (E-e sinE-M)/(1-e cosE) up to 50 times until the step is below 1e-13, and return E rounded to 9 decimals.

Why this case matters

Orbit determination and mission planning chain many small conversions; one wrong branch or unit silently moves a spacecraft by kilometres.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
elliptic kepler solver [-8.0, 0.75]	`-8.567196702`	`3.999173912`	Failed

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