I am using this code to draw a graph with errors from a txt file:
TGraphErrors *g = new TGraphErrors("myFile.txt");
"x axis title;"
"y axis title");
g->Draw("AP"); //"P" is a must to activate the above "SetMarkerStyle"
if (gPad) gPad->SetLogy(0);
However, I get this (no error bars shown):
What does the “myFile.txt” contain?
Just normal X and Y data points:
and so on.
So, you do not provide errors at all.
I added like three set of values for Y so root can calculate the std deviation. Isn’t that how it works?
What are you talking about?
See the constructor reading input from a file: TGraphErrors::TGraphErrors
Ok I did the measurements like 3 times and ended up with:
X1 X2 X3 Y1 Y2 Y3
So these are columns of data for which I could manually calculate errors, but I wanted to do it automatically in root.
You need to write a loop over your data and calculate everything yourself.
Yes I see it now. Thanks.
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