### New Parabolic Trendline

 New Parabolic Trendline

```//www.aflcode.com
Plot(C,"C",1,64);
perc=3;//sensitivity calibration
x=BarIndex();xx=LastValue(x);
t1=LastValue(ValueWhen(PeakBars(H,perc)==0,x));
H1=LastValue(ValueWhen(PeakBars(H,perc)==0,H));
t11=LastValue(ValueWhen(TroughBars(L,perc)==0,x));
H11=LastValue(ValueWhen(TroughBars(L,perc)==0,L));
g=t1>t11;
shape=IIf(g,shapeDownArrow*(x==t1),shapeUpArrow*(x==t11));
Color=IIf(g,colorRed,colorBrightGreen);
PlotShapes(shape,color);
t=IIf(g,x-t1,x-t11);
diff1=IIf(g,H1*(xx-t1),H11*(xx-t11));
Lma=LastValue(MA(C,50));
f1=0;f2=IIf(Lma<100,1,0)+3*int(log10(Lma));
fa=0;fb=0;step=f2/100;
for(f=f1;f<f2;f=f+step)
{
parabolic=IIf(g,H1-f*t^2,H11+f*t^2);
S1=LastValue(Sum(abs(parabolic-H),xx-t1));
S11=LastValue(Sum(abs(parabolic-L),xx-t11));
diff=IIf(g,S1,S11);
if(diff<diff1)
{
diff1=diff;fa=f;
}
}
for(f=Max(fa-step,0);f<fa+step;f=f+0.01*step)
{
parabolic=IIf(g,H1-f*t^2,H11+f*t^2);
S1=LastValue(Sum(abs(parabolic-H),xx-t1));
S11=LastValue(Sum(abs(parabolic-L),xx-t11));
diff=IIf(g,S1,S11);
if(diff<diff1)
{
diff1=diff;fb=f;
}
}
p=IIf(g,H1-fb*t^2,H11+fb*t^2);
Plot(IIf(x>Max(t1,t11),p,-1e10),"",color,1);
Title=Name()+", "+WriteIf(t1>t11,"f_desc","f_asc")+"="+WriteVal(fb,1.4);

/* Old
//The best-fit parabolic after the last peak
Plot(C,"C",1,64);perc=5;
x=BarIndex();xx=LastValue(x);
t1=LastValue(ValueWhen(PeakBars(H,perc)==0,x));
H1=LastValue(ValueWhen(PeakBars(H,perc)==0,H));
PlotShapes(shapeDownArrow*(x==t1),colorRed);
t=x-t1;diff1=H1*(xx-t1);f1=0;f2=2;fa=0;fb=0;step=0.01;
for(f=f1;f<f2;f=f+step)
{
parabolic=H1-f*t^2;
diff=LastValue(Sum(abs(parabolic-H),xx-t1));
if(diff<diff1)
{
diff1=diff;fa=f;
}
}
for(f=Max(fa-step,0);f<fa+step;f=f+0.1*step)
{
parabolic=H1-f*t^2;
diff=LastValue(Sum(abs(parabolic-H),xx-t1));
if(diff<diff1)
{
diff1=diff;fb=f;
}
}
Plot(IIf(x>t1,H1-fb*t^2,-1e10),"",colorRed,1);
Plot(IIf(x>t1,H1-Max(fa-step,0)*t^2,-1e10),"",colorBlack,1);
Plot(IIf(x>t1,H1-(fa+step)*t^2,-1e10),"",colorBlack,1);
Title=Name()+", fa="+WriteVal(fa,1.3)+", fb="+WriteVal(fb,1.3);

/* fa is the first approximation [2 decimals] AND fb is the most
accurate [3 decimals]
The [red] best-fit parabola AND the [black] nearest neighbours appear
on the price chart.
```

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