pds:=Input("Weekly EMA periods",1,520,4);
shift:=1+Input("EMA vertical shift %",
 -100,100,0)/100;
EOW:=Input("Final week's end:  [1]True,  [2]Current (dynamic)",1,2,2);
plot:=Input("plot:  [1] EMA,  [2] Crossover signals",1,2,1);

{ Choice of Static/Dynamic last EOW signal }
EOW:=If(EOW=2,Cum(1)=LastValue(Cum(1)),
 Cum(1)=LastValue(Cum(1)) AND DayOfWeek()=5);

{ Reference EOW signals }
WkEnd:=EOW OR
 FmlVar("Week's true Start & End","WEEKEND");

{ Week's Close }
WkCl:=ValueWhen(1,WkEnd,C);
WkCl:=ValueWhen(1,WkCl<>0,WkCl);

{ Reduce periodicity if insufficient periods }
pds:=If(pds>Cum(WkEnd),Cum(WkEnd),pds);

{ Weekly EMA }
WkEma:=ValueWhen(1,WkEnd,PREV)
 *(1-2/(pds+1))+WkCl*2/(pds+1);

{ Vertical shift }
WkEma:=WkEma*shift;

{ Crossover signals }
signals:=Cross(C,WkEma)-Cross(WkEma,C);

{ Plot on price chart }
If(plot=2,signals,WkEma)