[ericpruitt]

I adapted the same moonphase logic for the status line program I use with dwm. Did you run into any discrepancies with using January 0 vs December 31st? Some of the translations of Walker's as noted in my comment at https://github.com/ericpruitt/emus/blob/ea059239845ee6d57614... seem to produce differing results.

[oliverkwebb]

This discrepancy with time is explained in the book the algorithm is based on (Practical Astronomy with Your Calculator, which also does a good job explaining a ton of other ideas and models in astronomical calculation).

January 0th makes sense because a year starts on January 1st. You count days of the year from 1 instead of from 0. So if we are going by the day of the year, day 1 of the year should be Jan1, the consequence of this being that Jan0 exists and is Dec31 of the prev year.

I originally got into this because of my status bar on i3, hacking together C code from moontool into https://github.com/oliverkwebb/moontool about a year back.

[hulitu]

> January 0th makes sense because a year starts on January 1st. You count days of the year from 1 instead of from 0. So if we are going by the day of the year, day 1 of the year should be Jan1, the consequence of this being that Jan0 exists and is Dec31 of the prev year.

That's how bugs get introduced. /s