Daily Volume Indicator- DVI for Amibroker (AFL)

_SECTION_BEGIN(" DVI ");
function DailyVolumeIndicator()
{
  midpoint = ( High + Low ) / 2;
  dv = Volume * (( Close - midpoint ) / midpoint);
   return Cum( dv );
}
Period= Param("period",21,1,100,1);
r1=DailyVolumeIndicator();
r2=TEMA( 2*TEMA(r1,int(Period/2))- TEMA(r1,Period),int(sqrt(Period)));
Plot( r2, _DEFAULT_NAME(), IIf( r2> Ref(r2,-1) , ParamColor("Up Color",
colorBlue ), ParamColor("Down Color", colorRed ) ));
_SECTION_END();