Cogre Method of Finding weekday of Gregorian date without calendar (Updated)
Cogre Day Method
(Cogre - Co6 Gregorian)
Given date: D-M-Y 1. Find the Cogre Year Number (Cy)
For January and February, Cy = (Y-1) + Int((Y-1)/4) - Int((Y-1)/100) + Int((Y-1)/400)
For other months, Cy = (Y-1) + Int(Y/4) - Int(Y/100) + Int(Y/400)
Int(x) = Integer Part of x
Month Index
|
Months
|
Months
|
Months
|
0
|
1
|
10
| |
1
|
5
| ||
2
|
8
| ||
3
|
2
|
3
|
11
|
4
|
6
| ||
5
|
9
|
12
| |
6
|
4
|
7
|
|
Month
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
12
|
|
Cm
|
0
|
3
|
3
|
6
|
1
|
4
|
6
|
2
|
5
|
0
|
3
|
5
|
3. Find Cogre Day Number Cd = Cy+Cm+D
4. Find Cogre weekday,
Q=Cd/7;
Cw = [ Q-Int(Q) ] * 7
5. Find the weekday as per given table:
Cw
|
Weekday
|
0
|
Sunday
|
1
|
Monday
|
2
|
Tuesday
|
3
|
Wednesday
|
4
|
Thursday
|
5
|
Friday
|
6
|
Saturday
|
Example:
D-M-Y: 12.08.2015
D=12, M=8, Y=2015
Cy = (2014)+Int(2015/4)-Int(2015/100)+Int(2015/400)
Cy = 2014 + Int(503.75) - Int(20.15) + Int(5.0375) = 2014+503-20+5 =2502
Cm= 2
Cd = Cy+Cm+D = 2502+2+12 = 2516;
Q=2516/7 = 359.4285;
Cw=7*(359.4285-359)=3 = Wednesday;
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