My on-line friend Al Vachris recently sent me a link to the Tropical Events site, which features a detailed analysis of the orbital motion of the Earth and the other bodies of the solar system, all done in Excel, and all available for free download:
This is a great site, and well worth a visit for anyone interested in astronomy or the scientific application of Excel, but what really grabbed my interest was that the author had used the XNumbers add-in in preparing his charts, and he had got his brother to update the program for Excel 2007/2010.
Xnumbers is a free open-source maths add-in, offering a huge number of additional maths functions and extended precision arithmetic. It was developed by Leonardo Volpi and the “Foxes Team” in Italy, but it had not been updated for Excel 2007. Steve Beyers, the author of the Tropical Events site, got his brother, John Beyers, to do the necessary update, and also to compile the functions with a resulting performance improvement. The new version, XNumbers6.0, can be downloaded from:
The download includes an excellent detailed help file. Further information is available at:
The Foxes Team site Detailed documentation of XNumbers and related maths topics from the original authors.
It is excellent news that this software is now available for Excel 2007/2010, and I recommend the sites linked above to anyone wanting to do advanced numerical analysis inside Excel.