Marva Mid R-Line Signal for Amibroker (AFL)

_SECTION_BEGIN("Marva Mid R-Line Signal");
x = Cum(1);
lastx = LastValue( x ); 
Daysback = 10; 
aa = LastValue( LinRegIntercept( Close, Daysback) );
bb = LastValue( LinRegSlope( Close, Daysback ) );

y = Aa + bb * ( x - (Lastx - DaysBack) ); 
//Plot( Close, "Close", colorRose, styleCandle );
Plot( IIf( x >= (lastx - Daysback), y, -1e10 ), "LinReg", colorYellow );
per1=Param ("per1", 0.325,0.1,50,0.10);

perc=per1;
x1=BarIndex();xx=SelectedValue(x);
t1=SelectedValue(ValueWhen(PeakBars(C,perc)==0,x)) ;
H1=SelectedValue(ValueWhen(PeakBars(C,perc)==0,C)) ;
t11=SelectedValue(ValueWhen(TroughBars(C,perc)==0, x));
H11=SelectedValue(ValueWhen(TroughBars(C,perc)==0, C));
g=t1>t11;
shape=IIf(g,shapeHollowDownTriangle*(x==t1),shapeHollowUpTriangle*(x ==t11));
Color=IIf(g,colorRed,colorBrightGreen);
PlotShapes(shape,color);

_SECTION_END();