yes,
it does not work in that way. Fill the myClose with some sample data and than check the math. When the calculation will be ok will fix the first part.

delete the
StartDate= 20060101;
EndDate = 20060601;

BarPeriod = 15;

just plain c

I tried with the following code without success, sorry I'm a newbie:

#define N 10 // Number of bars

function run()
{

var myClose[10] = { 1,3,9,4,12,6,5,10,15,5};
var LR_line[10];

// variables
var a,b,c,sumy=0.0,sumx=0.0,sumxy=0.0,sumx2=0.0,h=0.0,l=0.0;
int x,i;
int barsToCount=50;


for( i=0; i<N; i++)
{
sumy+=myClose[i];
sumxy+=myClose[i]*i;
sumx+=i;
sumx2+=i*i;
}

c=sumx2*N-sumx*sumx;

// Line equation
b=(sumxy*barsToCount-sumx*sumy)/c;
a=(sumy-sumx*b)/N;

for(x=0;x<N;x++)
{ LR_line[x]=a+b*x;
plot("NEW_linreg", LR_line[x],MAIN, RED);
}




}

The calculation should be correct; the issue is related how to plot the straight line in a time chart.

This is another example from cAlgo :

using System;
using cAlgo.API;
using cAlgo.API.Internals;
using cAlgo.API.Indicators;

namespace cAlgo.Indicators
{
[Indicator(IsOverlay = true, AccessRights = AccessRights.None)]
public class LinearRegressionChannel : Indicator
{
[Parameter(DefaultValue = 200)]
public int Bars { get; set; }

[Parameter(DefaultValue = "Yellow")]
public string Color { get; set; }

[Parameter(DefaultValue = 1.0)]
public double LineThickness { get; set; }

[Parameter("Center", DefaultValue = true)]
public bool ShowCenter { get; set; }

[Parameter("Channel", DefaultValue = true)]
public bool ShowChannel { get; set; }

[Parameter("Standard deviation", DefaultValue = true)]
public bool ShowDeviantion { get; set; }


private Colors color;

protected override void Initialize()
{
// Parse color from string, e.g. "Yellow", "Green", "Red". string must start with large letter, "Red" is valid, "red" - not.
if (!Enum.TryParse(Color, out color))
color = Colors.Yellow;
}

public override void Calculate(int index)
{
if (IsLastBar)
LinearRegression(MarketSeries.Close);
}

private void LinearRegression(DataSeries series)
{
// Linear regresion

double sum_x = 0, sum_x2 = 0, sum_y = 0, sum_xy = 0;

int start = series.Count - Bars;
int end = series.Count - 1;

for (int i = start; i <= end; i++)
{
sum_x += 1.0 * i;
sum_x2 += 1.0 * i * i;
sum_y += series[i];
sum_xy += series[i] * i;
}

double a = (Bars * sum_xy - sum_x * sum_y) / (Bars * sum_x2 - sum_x * sum_x);
double b = (sum_y - a * sum_x) / Bars;


// Calculate maximum and standard devaitions

double maxDeviation = 0;
double sumDevation = 0;

for (int i = start; i <= end; i++)
{
double price = a * i + b;
maxDeviation = Math.Max(Math.Abs(series[i] - price), maxDeviation);
sumDevation += Math.Pow(series[i] - price, 2.0);
}

double stdDeviation = Math.Sqrt(sumDevation / Bars);

// draw in future
end += 20;

double pr1 = a * start + b;
double pr2 = a * end + b;

if (ShowCenter)
{
ChartObjects.DrawLine("center", start, pr1, end, pr2, color, LineThickness, LineStyle.Lines);
}

if (ShowChannel)
{
ChartObjects.DrawLine("top", start, pr1 + maxDeviation, end, pr2 + maxDeviation, color, LineThickness, LineStyle.Solid);
ChartObjects.DrawLine("bottom", start, pr1 - maxDeviation, end, pr2 - maxDeviation, color, LineThickness, LineStyle.Solid);
}

if (ShowDeviantion)
{
ChartObjects.DrawLine("dev-top", start, pr1 + stdDeviation, end, pr2 + stdDeviation, color, LineThickness, LineStyle.DotsVeryRare);
ChartObjects.DrawLine("dev-bottom", start, pr1 - stdDeviation, end, pr2 - stdDeviation, color, LineThickness, LineStyle.DotsVeryRare);
}
}

}
}


thus the calculation should be fine but what about the plotting in Zorro?

Ciao,
the calculation for getting the line equation look correct to me, but I am not an expert on how plotting with Zorro.
Sorry