The #SūryaSiddhānta describes the time from the spring equinox to the autumn equinox as daytime for the gods and nighttime for the demons; the other half of the year is day for the demons and night for the gods. Perhaps this just means that demons like darkness, or it might mean that Indians thought summer on top of the world corresponded to winter underneath, there demons live.
7/11
When I was looking up #Indian #calendars, I read three different translations of the #SūryaSiddhanta because there are no other good descriptions in English (and the translations are hard to follow).
It's probably for the best I didn't try to read the #KālachakraTantra to figure out the #Tibetan calendar, because it is written in a bizarre, complex, and very poetic way. Edward Henning wrote an entire book on the calendar, and devoted chapter 5 to a translation and commentary.
I did it.
I actually did it.
On and off, for approximately two years, I've been trying to decipher the #SūryaSiddhānta's rules to determine the traditional Indian calendar. Today, I have finally succeeded. It feels a bit like my last day of school. I've been at this for so long, and now it's over, and the world is open ahead of me.
I mean, I'm still going to keep writing #Python. There are all sorts of calendars left, and modern panchangas tend to go by modern ephemerides.
Got up quite early for a night shift week. Had a nice breakfast, watched some YouTube, read some #JudgeDredd, took part in a #Splatoon3 challenge, and just now wrote a whole lot of #Python to compute the positions of the sun and the moon as described in the first two chapters of the #SūryaSiddhānta. I had to restart that part from scratch, and my code is now cleaner, more comprehensible, and seems to be doing what the book means.
Good day so far.
I've spent the last several months trying to decipher an 1860 English translation of the #SuryaSiddhanta, which was originally written in #Sanskrit and published in its final form in KY 3606 (505 AD). After tracing multiple errors and bugs, I've finally gotten a pretty accurate algorithm which agrees with the methods of late Classical Indian #astronomy as well as observations...
And it looks like modern Indian Solar New Year is actually synched to the #GregorianCalendar.
I've spent the last few months trying to work out how the epicyclic system of classical Indian astronomy works.
Today I realised I've been completely misunderstanding the sources. In fairness, the #SuryaSiddhanta is pretty vague in the name of maintaining a classical poetic form and was probably intended as a complement to in-person instruction. Ebeneezer Bugess' translation and commentary are hard to follow and riddled with cluttered, confusing diagrams and tangents.
I've done it!
Since I had some #Covid-related downtime, I've been teaching myself to program, and I've finally managed to implement #Python functions to compute the time of #sunrise and #sunset according to traditional #Indian methods.
Admittedly, I don't think my method is the same as the one described in the #SuryaSiddhanta, but the translation and commentary I was able to find are really vague and unclear about what to actually do. Mine at least is consistent with what was known at the time
The #SuryaSiddhanta's methods for calculating the positions of the sun and moon at times specify that the absolute value of the jya of an arc must be added to some value in some cases, and subtracted in others.
Since the jya is the predecessor to the modern sine, in this we see the earliest inklings of negative values of trigonometric functions. It's interesting how ideas develop.
Infrapink (he/his/him)