[ROOT] TGraph smooth curve option

From: Gero Flucke (gero.flucke@desy.de)
Date: Mon Jul 07 2003 - 19:39:47 MEST


Hi!
I noticed that for TGraph the draw option 'l' (simple poly-line) and 'c'
(smooth curve) behave different:

If the a point of a TGraph is outside the axis range of the previous drawn
histogram, than for 'l' the poly-line connects all points, i.e. the line
is drawn untill the border of the frame (as one wants it!). But for 'c'
the curve just ignores the points outside the range:

{
TH1* hist = new TH1F("hist", "hist", 20, 1, 10);
hist->SetBinContent(1, 5.);

TGraph* graph = new TGraph(6);
//graph->SetPoint(0, 1., 2.5);
graph->SetPoint(0, 0.99999, 2.5);
graph->SetPoint(1, 2., 1.5);
graph->SetPoint(2, 3., 1.5);
graph->SetPoint(3, 4.5, 4.);
graph->SetPoint(4, 5.5, 4.5);
graph->SetPoint(5, 7., 4.);

hist->Draw();
// graph->Draw("l");
graph->Draw("cl");
}

This is especially annoying if it is the first or the last point...
Is it a bug or a feature?
How to draw a smooth line just for exactly the range of the x-axis,
although first and last point defining the TGraph are outside the axis
range?

BTW: I am using root 3.04_02 on a linux PC.


Cheers

	Gero



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