The algorithms and programs in this directory are
based on the book by E. G. Richards, "Mapping Time: The Calendar and Its History,"
2000, The Oxford Press.

Notes herein are supplemental to the README* in the parent
directory and may supersede some information based on
testing.

The issue is Meeus and the basis for his tests:
what Julian Day number are we using for DateTime
which is a proleptic Gregorian calendar?

Mr. Richards makes a case for working with JDN 
but with Gregorian dates, so that seems to
be the best path ahead.

His mathematical notes from Chapter 23:

All numbers are whole numbers (except in algorithm H).

Division, denoted by '/', is "invariably" integral division.
Raku's equivalent is 'div';

The 'mod' (modulo) function, e.g., MOD(a,b) means integral
division A/B and return the integral remainder, if any, zero
otherwise. The Raku equivalent is: 'A mod B' where the arguments
and return value are integers.

We use the 'min' function to select the minimum of a pair
of numbers. Raku has that routine.

Notation and symbols
--------------------

Richards' formulae refer to D/M/Y as the given
calendar, D'/M'/Y' as the computational calendar,
and J as the common and unabiguously defined Julian day number (J)
for both.

For this implementation we shall use D'c/M'c/Y'c as the symbols for
the computational calendar (and suffix other variables with 'c as well).


