Plotting equation and datapoints on same graph

ROOT Version: 6.22
Platform: Root
Compiler: Root compiler


I want to plot the cylinder of equation x^2+y^2 = 25 and some data points(for example: 500 sample points with values of x,y,z) in a same 3D graph using TMultiGraph. But it giving the error like:

/home/subhrod/root/macros/cylinder.C:6:6: error: no matching member function for call to ‘Add’
f->Add(f1);
/home/subhrod/root/include/TMultiGraph.h:53:22: note: candidate function not viable: no known conversion from ‘TF3 *’ to ‘TGraph *’ for 1st argument
virtual void Add(TGraph *graph, Option_t *chopt="");

How do I resolve this problem?
With regards.

In order to draw both the cylinder and the data points, you can call Draw() on the function object and on a TGraph object. The second call should use the option same, like Draw("same"), in order to reuse the canvas.

Hi,
That command will overlap both of the graph in one canvas. But I want to plot the curves in same graph so that I can visualise it on 3D, which is not possible by “same” method

TMultiGraph does not accept TF3, as the error says; it only accepts Graphs (or other TMultiGraphs), see its constructors in the documentation. Maybe you can create the graphs as TGraph2D and use “same”, as there is no TMultiGraph2D.

Thank you.
I have solved the problem by generating datapoints and use TGraph.