Using a Date, Get the past Monday

tmp:=CreatedOn;
Rem {Monday is day 2};
tmpdayofwk:=@WeekDay(tmp);
Rem {Get difference from Monday};
tmpdiff:=tmpdayofwk-2;
Rem { if tmpdiff <0 then sunday and we need a week ago, else whatever tmpdiff is};
tmpdaysoff:=@If(tmpdiff<0; -6; tmpdiff * -1);
@Adjust(tmp;0;0;tmpdaysoff;0;0;0)

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Using a Date, Get the Current Week, Last Week, and the Week Before 
(3 weeks total)


tmp:=CreatedOn;
or
tmp:=@Date(@TextToTime("12/31/2003"));
or
tmp:=@Now;

REM { get the first day of this year };
firstDay := @Date(@Year(tmp);1;1);
lastDay:= @Date(@Year(tmp);12;31);
REM { get the week, add 1 to increase from display from 0-51/52 to 1-52/53
There may be more than 52 weeks depending on how many days are in 1st week};
basewk := @Round((tmp - firstDay)/86400/7) + 1;
lastwk:=@Round((lastDay - firstDay)/86400/7) + 1;
baseyr:=@Year(tmp);
REM{ calculate the previous weeks};
wk1:=@If(basewk-1<1; lastwk-basewk; basewk-1);
yr1:=@If(basewk-1<1; baseyr-1; baseyr);
wk2:=@If(basewk-2<1; lastwk-(basewk+1); basewk-2);
yr2:=@If(basewk-2<1; baseyr-1; baseyr);
@Implode((@Text(baseyr) + "-" + @Text(basewk)) : (@Text(yr1) + "-" + @Text(wk1)) : (@Text(yr2) + "-" + @Text(wk2)); ";")

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Using a Date, Get the Current Month, Last Month, and 2 Previous Months 
(4 months total)

tmp:=@Date(@TextToTime("01/01/2003"));
or
tmp:=@Now;

tmpm:=@Month(tmp);
tmpy:=@Year(tmp);
tmpmo:=@Right("0" + @Text(tmpm); 2);
tmpyr:=@Text(tmpy);
tmp1:=tmpm - 1;
tmpmo1:=@Right("0" + @Text(@If(tmp1<1; tmp1+12; tmp1)); 2);
tmpyr1:=@Text(@If(tmp1<1; tmpy-1; tmpy));
tmp2:=tmpm - 2;
tmpmo2:=@Right("0" + @Text(@If(tmp2<1; tmp2+12; tmp2)); 2);
tmpyr2:=@Text(@If(tmp2<1; tmpy-1; tmpy));
tmp3:=tmpm - 3;
tmpmo3:=@Right("0" + @Text(@If(tmp3<1; tmp3+12; tmp3)); 2);
tmpyr3:=@Text(@If(tmp3<1; tmpy-1; tmpy));
(tmpyr +"-" + tmpmo) : (tmpyr1 +"-" + tmpmo1) : (tmpyr2 +"-" + tmpmo2) : (tmpyr3 +"-" + tmpmo3)



tmpy:=@Year(tmp);