### 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

2. Cogre Month Number, Cm

 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;