Periods = 100;

function DarvasHigh( Periods )
{
	HHVtemp = HHV( High, Periods );
	result = HHVTemp;
	for( i = Periods + 4; i < BarCount; i++ )
	{
   		result[ i ] = IIf( H[ i - 3 ] >= HHVTemp[ i - 4 ] AND
                     H[ i - 3 ] > H[ i - 2 ] AND
                     H[ i - 3 ] > H[ i - 1 ] AND
                     H[ i - 3 ] > H[ i ],
                     H[ i - 3 ],
                     result[ i - 1 ] );
	}
	return result;
}

function NewDarvasHigh( Periods )
{
  dh = DarvasHigh( Periods );
  return dh AND Nz( dh ) != Ref( Nz( dh ), -1 );
}

function NewDarvasLow( Periods )
{
  dh = DarvasHigh( Periods );
  ndl = Ref( L, -3 ) < Ref( L, -2 ) AND
        Ref( L, -3 ) < Ref( L, -1 ) AND
        Ref( L, -3 ) < L AND
        Ref( H, -2 ) < dh AND
        Ref( H, -1 ) < dh AND
        H < dh;
  return Nz( ndl ) AND Ref( Nz( ndl ), -1 ) < 1;
}

function DarvasLow( Periods )
{
  return ValueWhen( NewDarvasLow( Periods ), Ref( L, -3 ) );
}

function DarvasBoxEnd( Periods )
{
	end = BarsSince( NewDarvasHigh( Periods ) ) <
       	BarsSince( Ref( NewDarvasLow( Periods ), -1 ) );
	return Nz( end ) AND NewDarvasLow( Periods );
}

function DarvasBoxHigh( Periods )
{
	dbe = DarvasBoxEnd( Periods );
	dbhi = ValueWhen( Nz( dbe ) AND NOT IsNull( Ref( dbe, -1 ) ),
       	DarvasHigh(       Periods ) );
	return IIf( Nz( dbhi ) == 0, H + 1e-6, dbhi );
}

function DarvasBoxLow( Periods )
{
	dbe = DarvasBoxEnd( Periods );
	dblo = ValueWhen( Nz( dbe ) AND NOT IsNull( Ref( dbe, -1 ) ),
        DarvasLow( Periods ) );
	return IIf( Nz( dblo ) == 0, L - 1e-6, dblo );
}

function DarvasPossSell( Periods )
{
	dsl = Low < DarvasBoxLow( Periods );
	return Nz( dsl ) AND Ref( Nz( dsl ), -1 ) < Nz( dsl );
}

Plot( C, "Price", colorBlack, styleCandle );
Plot( DarvasLow( 100 ), "DL", colorRed );
Plot( DarvasHigh( 100 ), "DH", colorGreen );