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Oblique Spherical Triangle toolbox

version (75.2 KB) by Rody Oldenhuis
solves the general oblique spherical triangle

1 Download

Updated 10 Jun 2018

GitHub view license on GitHub

This toolbox can solve any of the 6 possible subproblems associated with an oblique spherical triangle, when only 3 of the 6 angles are known.
The toolbox basically is an implementation of the set of tools developed in [Wertz, 2001], which aimed to fully automize the procedure and do away with the need of user intervention.


[b1, c1, C1, b2, c2, C2] = aas(A, B, a)

gives both solutions for the sides b and c and the angle C, when given angles A, B and side a. This particular problem can be called the Angle-Angle-Side problem, hence the name.

Both degrees and radians are implemented, the difference is indicating by appending a 'd' to the function name. The above example expects and returns radians, whereas

[b1, c1, C1, b2, c2, C2] = aasd(A, B, a)

expects and returns degrees.

[Wertz, 2001]
James R. Wertz, Mission Geometry: Orbit and Constellation Design and Management, 2001. Published by Microcosm and Kluwer Academic Publishers.

Comments and Ratings (2)

Whoah! I totally overlooked your comment! I actually found this comment by googling for one of my other submissions :s

Anyway, thanks for the comment. Actually, in MAL/MSL, that whole denominator is unneccesary, since the objective is to take the ATAN2. I posted an update which does just that. I also got rid of the whole MAL/MSL thing, and all dependencies I created back in a time I did not yet know DEAL() ^_^

Thanks for the feedback.

This comment is on the descriptive doc, not on the code. Specifically, it is about the auxiliary functions mal.m, mald.m, msl.m, and msld.m.

First, I think a correction is needed. In the equations for "cos c". the numerator has a plus sign which should be minus.

Second, a suggestion for a very minor improvement. The definitions of "sin c", "cos c", "sin C", and "cos C" all have the same denominator:

1 - sin a sin b sin A sin B

This is equal to

1 - (sin b sin A)^2

which contains only the given data b and A, not B which is a computed quantity (in ssa, the main user of the "middle side/angle laws"). So this expression has the advantage of avoiding any errors in the intermediate computation.


[linked to Github]

Found & corrected a few bugs

updated all files -- no dependencies should exist anymore.
Also got rid of H() and mal()/msl(); they were really just clutter.

MATLAB Release Compatibility
Created with R2008b
Compatible with any release
Platform Compatibility
Windows macOS Linux