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# Implement hyperbolic anomaly conversion functions#275

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opened this issue Oct 26, 2017 · 2 comments
Closed

# Implement hyperbolic anomaly conversion functions #275

opened this issue Oct 26, 2017 · 2 comments
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### astrojuanlu commented Oct 26, 2017 • edited

 馃悶 Problem We should have hyperbolic anomaly conversion functions, in the same way we have elliptic anomaly functions here: https://github.com/poliastro/poliastro/blob/v0.7.0/src/poliastro/twobody/angles.py Right now, using `nu_to_M` for eccentricity values higher than one gives NaN: ``````In [2]: from poliastro.twobody.angles import * In [3]: from astropy import units as u In [4]: nu_to_M(0.1 * u.rad, 1.5 * u.one) /home/juanlu/.miniconda36/envs/py36/lib/python3.6/site-packages/astropy/units/quantity.py:641: RuntimeWarning: invalid value encountered in sqrt *arrays, **kwargs) Out[4]: `````` 馃幆 Goal This is important since `Orbit.sample` uses the angle conversion functions to derive appropriate time values for propagation, and right now it doesn't work for hyperbolic orbits. 馃挕 Possible solutions We should implement these equations: (from Curtis "Orbital Mechanics for Engineering Students") However, there are limitations in the true anomaly values, so care should be taken: (from Vallado "Fundamentals of Astrodynamics") Finding references for validation proved to be a bit difficult, so I posted a question on Physics.SE here https://physics.stackexchange.com/q/365117/7641 馃搵 Steps to solve the problem Comment below about what you've started working on. Add, commit, push your changes Submit a pull request and add this in comments - `Addresses #` Ask for a review in comments section of pull request Celebrate your contribution to this project 馃帀 The text was updated successfully, but these errors were encountered:

### astrojuanlu commented Oct 26, 2017

 I'm labeling this as a bug to fix in 0.8.

mentioned this issue Oct 27, 2017

### anhiga commented Oct 27, 2017

 Closed by #276

closed this as completed Oct 27, 2017
removed the 1 - Ready label Oct 27, 2017
mentioned this issue Oct 27, 2017