//------------------------------------------------------------------------------
//
//  Formula Name:    Expiry Thursday for Indian markets
//  Author/Uploader: Ajay Joglekar 
//  E-mail:          
//  Date/Time Added: 2005-05-14 15:39:52
//  Origin:          Need to mark the expiry day of options every month in the indian market has prompted me to write this AFL which I felt like sharing.
//  Keywords:        India Option Expiry Thursday TripleWitching
//  Level:           semi-advanced
//  Flags:           indicator
//  Formula URL:     http://www.amibroker.com/library/formula.php?id=461
//  Details URL:     http://www.amibroker.com/library/detail.php?id=461
//
//------------------------------------------------------------------------------
//
//  This indicator will give a white arrow pointing the last thursday of every
//  month. This is the monthly expiry day in the indian markets.It is useful to
//  note changes in prices of futures and options.
//
//------------------------------------------------------------------------------

 function Lastthursday()
{
 Daysinmonth=IIf(Month()==1 OR Month()==3 OR Month()==5 OR Month()==7 OR Month()==8 OR Month()==10 OR Month()==12,31,30);
 Daysinmonthfeb=IIf(Year()%4 == 0 AND Year()%100!=0,29,28);
 Daysinmonthfinal=IIf(Month()==2,Daysinmonthfeb,Daysinmonth);
 returnvalue=IIf(Daysinmonthfinal-Day()<7 AND DayOfWeek()==4,1,0);
 return returnvalue;
}
Graph0=Close;
shape=IIf(Lastthursday(),shapeDownArrow,shapeNone);
PlotShapes(shape,colorWhite,0,Graph0,-24);