Re: Week of the year routine

["M. Lazarus" <mlazarus@xxxxxxxx>]

Booth,

 My initial reaction to the task was that I couldn't use the 
standard routines, since the week number was not standard.  It turned 
out much simpler than expected.  Pseudo code:

 Year to generate is passed to the program.

 Calendar file has 2 fields: Date and Week.

Init:
 WrkDate = %Date( PassedYear + '-01-01' )
 WrkWeek = 1

Process:
 DOW PassedYear = Year in WrkDate
    CHAIN WrkDate Calendar
    Date = WrkDate
    Week = WrkWeek
    Add / update record to Calendar

    Add 1 day to WrkDate
    IF DayOfWeek( WrkDate ) = 0   // Saturday, in this case
       Add 1 to WrkWeek
    ENDIF
 ENDDO

 That's pretty much the whole logic!

 -mark


At 4/15/2011 04:08 PM, you wrote:
> How about something like this?
>
> 1-Convert the target date to Julian Day.
> 2-Divide the Julian Day by 7.  That will give you a week number.
> 3-Save the remainder from your division.  It will range from 1 -7.
> 4-If the remainder is greater than zero, add one to the week number.
>
> Then the fun starts.  You have to find the offset vs the remainder to
> see if you need to add one more to your week number because of the day
> of the week that the year started.
>
> My bet is that what I am about to write won't really work, but it should
> show the algorithm, and you can finesse it from there.
>
> a-Find the day of the week for January 1st, UYEAR, as a number 0-6.
> b-add 1 to the day-of-week so that the range is 1-7.
> b-make a comparison with the remainder.  Some combination of that
> comparison will tell you whether or not to add 1 to the week number.
>
>
> --------------------------------------------
> (A day of the week calculation is here:)
> http://www.martinvt.com/Code_Samples/Date_Math/date_math.html
>
> note: This initializing date is easiest if you set it for the first date
> of your week, so that day that is the first day of the week become day
> 0. It might even be useful to set it to the beginning of the week on or
> before January 1.
>
>    D wTestDate       s               d   inz(d'2010-01-04')
>
> ------------------------------------------------------------------------
>
> Anyway, this may give you some thoughts to play with, even if V5R3 does
> not support true date fields.
>
>
>
>
> On 4/15/2011 11:23 AM, M. Lazarus wrote:
> >    Before I reinvent the "calendar file" wheel, does anyone have an
> > *RPG* routine that will calculate the week of the year.
> >
> >    A few parameters:
> >
> > - This machine is on an older OS version (5.3) and does not have the
> > SQL feature installed.
> >
> > - Week 1 of the year starts on January 1.  So, for example, in 2010,
> > Dec. 26-31 would be the last week of the year (53?).  Saturday, Jan
> > 1, 2001, is week 1.  Monday, Jan 2-8, is week 2, etc.
> >
> >
> >    Thank you.
> >
> >    -mark