Using Monday, Friday or Sunday dates to find relating month, If last week of a month has a Wednesday, then that week is part of same month

[atearth]

I'm currently trying to using Monday, Friday or Sunday dates to find relating month, to show week X is part of month Y.

[TABLE="class: grid, width: 475"]
<tbody>[TR]
[TD][/TD]
[TD]A[/TD]
[TD]B[/TD]
[TD]C[/TD]
[TD]D[/TD]
[/TR]
[TR]
[TD="align: right"]1[/TD]
[TD]Week Commencing Monday[/TD]
[TD="align: right"]30-Jan-17[/TD]
[TD="align: right"]29-Jan-18[/TD]
[TD="align: right"]28-Jan-19[/TD]
[/TR]
[TR]
[TD="align: right"]2[/TD]
[TD]Week Ending Friday[/TD]
[TD="align: right"]03-Feb-17[/TD]
[TD="align: right"]02-Feb-18[/TD]
[TD="align: right"]01-Feb-19[/TD]
[/TR]
[TR]
[TD="align: right"]3[/TD]
[TD]Week Ending Sunday[/TD]
[TD="align: right"]05-Feb-17[/TD]
[TD="align: right"]04-Feb-18[/TD]
[TD="align: right"]03-Feb-19[/TD]
[/TR]
[TR]
[TD="align: right"]4[/TD]
[TD]Month[/TD]
[TD="align: right"]01-Feb-17[/TD]
[TD="align: right"]01-Jan-18[/TD]
[TD="align: right"]01-Jan-19[/TD]
[/TR]
</tbody>[/TABLE]


B4 is 01-Feb-17 due to the week in question only having Monday & Tuesday in Jan-17. So the week in question would be part of Feb-17.

C4 and D4 would be 01-Jan due to both weeks in questions having Monday, Tuesday and Wednesday in Jan-YY.
Any ideas as to what formula to use?

Would leap day affect the formula used?

 

[James006]

Hello,

Not sure to fully understand your objective ...

Could the WeekNum() function applied to B1,C1,D1 be of any help ?