Lagrangian Interpolation

This is a technique that interpolates a function from tabulated values. An arbitrary number of tabulated values may be used, and they may have any arbitrary spacing. This program includes Point and Table structs so we can make use of the function, but in general, it would be best to modify this source to suit a larger program, and drop it in as a routine.

Usage

With gnuplot

Do

cargo run > output.dat

to run the program, load the points to a file, and

cargo test

to run the test(s)! Easy!

To plot the data with gnuplot, do the following:

gnuplot lagrangian_interp.plt > plot.png

to store the output in a .png file. If you want another format, read gnuplot's docs! They're pretty detailed.

With plotly

First, checkout the branch "plotly" like so:

git switch plotly

and then do

cargo run

and it will open an interactive graph in your default browser/webview. This makes use of the plotly crate, which interfaces with the plotly.js library, and gives Rust Jupyter-Notebook-level data visualization capabilities. Check it out!

Credit

The implementation was guided by this excellent textbook on Celestial Mechanics. Eventually I hope to have a program that can plot an entire ephemeris from initial conditions, but it turns out orbital mechanics is hard, so don't hold your breath.

You may have the source of this particular crate under the terms of the BSD 2-clause license, or any similar no-strings-attached OSS license.