My name is Karl-Heinz Lewin. On this website I would like to deal with the Computus Paschalis, the ancient and medieval Easter calculation, with the modern Easter calculation, with calendars, calendar calculations, calendar conversions from one calendar system to another, with planetary astronomy, as far as it is relevant for the Easter or calendar calculation, with programming languages and their respective quirks, with natural languages and their interconnections, with the German language and its flattenings, with scripts and alphabets and their decipherments.
21.05.2024
In The Easter Calendar Stone of Ravenna,
my current analysis, and in the JavaScript file
osterrechner/cyclopaschalisravenna.js,
the starting value for the Easter moon
had to be corrected, because the starting value 36 is of course only valid if for the starting year 'annus'
the expression ( annus - 1 ) modulo 19 yields 0.
For other start years, the algorithm returned nonsensical values.
To ensure that the calculation works for every starting year, the starting value for the Easter moon
is calculated using a formula that cannot be derived directly from the values on the Easter calendar stone,
but requires a mathematical abstraction: The rule for calculating the Easter moon in the next year
by subtracting 11 or conditional addition of 19 given in the first paragraph of this chapter corresponds to
a subtraction of ( 11 times the number of the previous year modulo 19 ) modulo 30,
the two constants involved can be found by trial and error.
This results in a start value for the Easter moon as
Easter moon start = 50 - ( 11 * ( py mod 19 ) + 14 ) mod 30, where py = the year number of the previous year.
With this change,
The Ravenna Easter calendar stone as a table calculator
now provides correct Easter Moon and Easter Sunday dates for any starting year from 1 to 4996.
28.02.2024
The algorithm for calculating the Easter date in the Julian calendar published in 2005 in my first article on the Easter calendar stone in Ravenna in Zeitensprünge 2005.2 and since 17 June 2023 on this website was faulty, a column was missing and thus an intermediate step in the calculation. (But nobody tried the algorithm, so nobody noticed that it was wrong.) The error has now been corrected, see under [Computus Paschalis: Antique Easter calculation].
19.02.2024
A presentation of the algorithm of the Easter calculation of Beda Venerabilis can now be found at [Computus Paschalis: Antique Easter calculation], and an Easter calculator that implements this algorithm, as well as a comparison programme that shows the results of the Easter calculation algorithms of the Easter calendar stone of Ravenna and the Easter tables of Dionysius Exiguus and Beda Venerabilis side by side for comparison, can be found at [Interactive Antique Easter calculators].
12.02.2024
A presentation of the algorithm of the Easter calculation of Dionysius Exiguus can now be found at [Computus Paschalis: Antique Easter calculation], and an Easter calculator that implements this algorithm, as well as a comparison programme that shows the results of the Easter calculation algorithms of the Easter calendar stone of Ravenna and Dionysius Exiguus side by side for comparison, can be found at [Interactive Antique Easter calculators].
30.11.2023
Three years ago, I came across writings by Kiev professor Iurii Mosenkis on the platform academia.edu, in which he deals with the decipherment of the Cretan linear script A and comes to the conclusion that the language is a Greek dialect.
In fact, there is no lack of attempts to decipher the few surviving written documents in Linear A on the assumption of one or other language or language family - however “many consider themselves qualified, but only a few are predestined” [Tabary in the comic series “Iznogoud”]:
I will leave it at the examples given. Presumably each of these authors has recognised one or other of the word equations correctly – there are probably Hattic, Hurrian and Semitic (Akkadian) words in Minoan texts (I consider Hungarian and Japanese words to be far-fetched), just as there are Hebrew (Jubel), Arabic (Magazin) and Turkish (Kiosk) words in the German language. However, the suffixes cited by Mosenkis and the prefix a as well as the pictorial representations (puppy = skylax for Scylla, knee for Knossos, spider = Arachna for Ariadne / Arihagna, etc.) have convinced me that Mosenkis interpreted the texts correctly.
The results of the works of
I have summarised the work of Mosenkis and his findings in the article “Linear A is deciphered – the language is Greek” (to be found on the navigation bar under [Scripts and Languages]).
03.11.2023 / 26.06.2023
I have completely revised my article about the Easter calendar stone of Ravenna and limited it to the topic of this marble tablet. Finally, I explain the algorithm found in this tablet and present two implementations (as an Excel spreadsheet and in JavaScript) with the possibility to visually compare the recalculation of the Easter tablet by the JavaScript implementation with the summarised reading of the original, the Easter calendar stone. Today, also the English version of this revision is ready. (To be found on the topic sheet under [Computus Paschalis: Antique Easter calculation].)
21.06.2023
Today I put my first Easter calculator on my website
(see under [Interactive Antique Easter calculators]).
It implements the algorithm of the Ravenna Easter calendar stone with selectable start year and selectable
time span (number of years), once in modern representation and the other one in antique representation.
Note that the start year 1 almost certainly corresponds to the year 532 C.E.
With the default setting (start year: 1, number of years: 95), the antique representation
should correspond exactly to the values of the Ravenna Easter calendar stone with a few exceptions.
The antique representation allows a tabulation up to the year MDCCCCLXXXXↅIII (1999) at the most.
Since this corresponds to the year 2530 C.E., I have refrained from implementing the representation
of even larger numerical values in Roman numerals according to the notation of the Easter calendar stone.
Translated with www.DeepL.com/Translator (free version)
17.06.2023
As a first article, I present here an English translation of an updated German version of my first publication dealing with the marble Easter tablet in the Archbishop’s Museum at Ravenna and its possible implications for the doubts expressed elsewhere <karl-der-große.de> about the validity of our believed chronology. (To be found on the topic sheet under [Computus Paschalis: Antique Easter calculation].)
Kind regards
Karl-Heinz Lewin