simple-elpmpp02

ELP/MPP02 (Ephemeride Lunaire Parisienne / Lunar Solution) provides highly accurate positions for the Moon over a time span of several thousand years. This Rust library is a port of the original ELP/MPP02 implementation, which can be found at ftp://cyrano-se.obspm.fr/pub/2_lunar_solutions/2_elpmpp02/

Several optimizations have been applied:

• SIMD (Single Instruction, Multiple Data)
• Ignoring small terms using the tol parameter

Like the original implementation, this library operates based on the dynamical frame of the mean ecliptic and equinox of J2000. The time scale of t is TT (Terrestrial Time).

Usage

Basic Usage

Here's a basic example of how to use the library:

use simple_elpmpp02;

fn main() {
    const J2000: f64 = 2451545.0; // 2000-01-01, 12:00:00 TT
    let coords = simple_elpmpp02::cartesian(J2000, 0.0);
    
    println!("Moon's position on 2000-01-01:");
    println!("X : {} km", coords.0);
    println!("Y : {} km", coords.1);
    println!("Z : {} km", coords.2);
    println!("X': {} km/d", coords.3);
    println!("Y': {} km/d", coords.4);
    println!("Z': {} km/d", coords.5);
}

Scripts

• elpmpp02.py: Supports the following features:

  • Downloads the official ELP/MPP02 implementation and coefficients from the source.
  • Replicates the functionality of the original implementation.
  • Generates .bin files. You may need to modify this file if you want to reduce the bin file size.

• generate_testcases.py: Reads ELPMPP02.PY.TXT (the output of elpmpp02.py) and prints the test function.

Acknowledgements

This implementation is based on the ELP/MPP02 theory developed by J. Chapront and G. Francou at the Bureau des Longitudes, Paris.