This section contains algorithms to handle a variety of general purpose calendrical computations for the old Julian and modern Gregorian calendar systems.  The calendar-related programs created for this web site are based on these algorithms written in PHP.

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At present, calendrical and time functions across programming language platforms is very inconsistent.  For example, not every programming language has a Julian day number function and/or Inverse JD number function for handling some general purpose calendar date and time-related computations.

The languages that do have calendrical functions, often have different functions and/or syntax that make it problematic when attempting to translate the same program into another language that lacks those date/time functions.

This section presents some basic general algorithms for doing calendrical computations from scratch without dependence on any special built-in proprietary or language-specific date/time functions.

It may be useful to have such a set of universal algorithms easy to translate into several programming languages.