0626
xiiii
xviii
ii
xvi
xv k.Maii
Apr 17
xii k.Maii
Apr 20
xvii hend.
The leftmost column in this table gives a year number pertaining to the feast of Easter described in each line, and to the indiction:
column 1 =(in the second part of the table:) the year number Y of the incarnation =(in the first part of the table:) the Diocletian year number D = Y - 284
Column 1 has the prefix "B" (for bissextum) if Y mod 4 = D mod 4 = 0.
The other columns are all related to Y, as follows:
column 2 = 1 + (2 + Y)mod 15 (see [Argumentum 2]) column 3 = ((Y mod 19)*11) mod 30 (see [Argumentum 3]) column 4 = 1 + (3 + floor( Y*5/4 ))mod 7 (see [Argumentum 4]) column 5 = 1 + (Y - 3)mod 19 (see [Argumentum 6]) column 6 = March 21 + (15 - 11*( Y mod 19))mod 30 d (see [Argumentum 14])
Column 8 has the postfix "ogd." (for ogdoadas) if Y mod 19 = 8 - 1 and the postfix "hend." (for hendeka) if Y mod 19 = 11 + 8 - 1.
We have indicated extreme values in columns 6, 7, 8 with asterisks.
ARGUMENTA PASCHALIA
Incipiunt argumenta de titulis paschalibus ¦gyptiorum investigata solertia ut praesentes indicent.
This begins the argumenta on the determination of Easter by the Egyptians, carefully investigated as shown in the following.
Argumentum primum. De annis Christi.
Si nosse vis quotus sit annus ab incarnatione Domini nostri Jesu Christi, computa quindecies XXXIV, fiunt DX; iis semper adde XII regulares, fiunt DXXII; adde etiam indictionem anni cujus volueris, ut puta, tertiam, consulatu Probi junioris, fiunt simul anni DXXV. Isti sunt anni ab incarnatione Domini.
First Argumentum. On the years of Christ.
If you want to find out which year it is since the incarnation of our Lord Jesus Christ, compute fifteen times 34, yielding 510; to these always add the correction 12, yielding 522; also add the indiction of the year you want, say, in the consulship of Probus Junior, the third, yielding 525 years altogether. These are the years since the incarnation of the Lord.
That the year numbers Y employed here agree with the usual Julian year numbers J is shown by the formulae for the indiction in [Argumentum 2] (using Y mod 15), for the epacts in [Argumenta 3 and 11] (using Y mod 19), and for the day of the week in [Argumentum 4] (using Y mod 28).