Hindu Holidays Rules
Hindu holidays recurrence rules are either based on the Hindu Lunar Calendar or the Hindu Solar Calendar. Most Hindu holidays are based on the Lunar Calendar.
Hindu Lunar holidays are based on a lunar month-day-time triplet.
Deepavali in Singapore
The calculation of Hindu Lunar holidays is extremely complex and requires repeated trial and errors tests by the program. Therefore it is normal for the sample dates to take a noticeable amount of time (about 1 second) to display each time you modify, or display, a Hindu Lunar holiday recurrence rule.
There are 2 types of Hindu Solar holidays:
Most are simply based on a solar month-day pair.
Tamil New Year, India
But some also depend on the Nakshatra: