From: CellShocked on
On Mon, 25 Jan 2010 08:54:43 -0500, Ron Rosenfeld
<ronrosenfeld(a)> wrote:

>On Mon, 25 Jan 2010 04:30:01 -0800, Paul Janssen <Paul
>Janssen(a)> wrote:
>>Hello, we encountered a faulty weeknumber generated by MX Excel for all dates
>>in 2010 as of Jan 3d, 2010. This should be weeknumber 1 until January 9th,
>>2010 but MX Excel uses weeknumber 2. As a result all consecutive weeks in
>>2010 are numbered 1 week too high.
>>Would be nice if MS could issue a repair patch!
>>regards, Paul Janssen
>It really depends on how you define weeknumber.
>The Excel WEEKNUM function behaves exactly as documented in HELP. "The WEEKNUM
>function considers the week containing January 1 to be the first week of the
>And you can choose whether your week should start on Sunday or Monday. If you
>want your weeks to start on Monday, then enter the appropriate return argument
>into the function and Jan 3, 2010 will fall into Week 1, giving you the results
>you apparently desire.
>I will also point out that there is an ISO standard for weeknumbers, which I'm
>told is used extensively in Europe. However, that standard would not return
>week 1 for 2010-Jan-3 through 2010-Jan-9 as that standard calls for weeks to
>start on Monday; and 2010-Jan-3 is a Sunday (and so would be week 53 under that

I find it annoying that in a year that has always been only 52 weeks
long, that a standards organization would adopt a "standard" where a
"week 53" gets utilized. It just caused an issue on our production floor
two weeks ago with respect to date coding for product serialization
purposes, which is where the entire system was derived from to begin

So what did those *they* people arrive at 5 decades ago? I am quite
sure there will be a mil standard somewhere. Regardless of what day of
the week it is or how it makes one's calendar appear to the eye, the week
that contains 1 January should be called "week 1". The week that
contains the last 5 days of December should be called "week 52". It does
not get much more simple than that.

Worrying about the fact that we print a calendar with the same day at
the left edge of the grid has only muddied the fact. Numbered weeks in a
year do not have a set "first day of the week" Week numbering is a
function of the number 7 and the number 365.

That is the US std (or was). I too remember reading about the
variances and alternate "conventions" being utilized, however.

The dude could make a custom "WEEKNUM_EU()" function. :-)
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