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I’m a lifelong learner and like to try out interesting or novel programming languages. I’ve coded up solutions to the direct and indirect problems of geodetics in Haskell, F#, Unison, Koka, and Rust. Occasionally I find problems with newer compilers but this is to be expected.

The Direct or Forward Geodetics Problem

• {x} The departure point on the ellipsoid.
• {α₁} The azimuth from the departure point.
• {s} The distance to the arrival point.

Given the above inputs, find:

• {y} The arrival point.
• {α₂} The azimuth at the arrival point.

The Inverse or Reverse Geodetics Problem

• {x} The departure point.
• {y} The arrival point.

Given the above inputs, find:

• {s} The distance between departure and arrival points.
• {α₁} The azimuth at the departure point.
• {α₂} The azimuth at the arrival point.

Geodetics Solutions

At the github/flight-earth organisation you’ll find a set of solutions to geodesy problems in various programming languages (listed chronologically).

flight-earth for Haskell

Uses the uom-plugin for units of measure.

meridian-arc for F#

Also published on nuget as meridian-arc. Interestingly, the math doesn’t work quite the same on all platforms (Windows, Mac and Ubuntu) I tested with.

flat-earth for Unison

Also published on unison share.

coriolis-effect for Koka

The docs for this language are nice, succinct and helpful.

oblate-spheroid for Lean

Doing inline doctest-like testing is nice in this language:

/-- info: 359° -/
#guard_msgs in #eval normalizeDeg $ Deg.mk (-1.0)

auxillary-sphere for Rust

Half converted by hand and half with the help of GitHub Copilot from the Lean4 solution.

Issues Found Incidentally

• koka-lang/koka
  Found issues compiling flight-earth/coriolis-effect.
• unisonweb/unison
  Found issues compiling flight-earth/flat-earth.