[ROOT] Drawing a function

From: Kalen Martens (fmartens@physics.utoronto.ca)
Date: Tue May 20 2003 - 21:28:54 MEST 

Hi,

I am having some difficulty in drawing a function that I have in a file.
Here is a simple function, for example:

>cat testfunc.C 

double testfunc(double x)
{
  double s;

  s=sin(x);

  return s;
}

I have a more complicated function in mind, but this is simple and I get
the same behavior. 

In ROOT (3.04/02), I do the following:

>root

Compiled for linux with thread support.

CINT/ROOT C/C++ Interpreter version 5.15.68, Dec 12 2002
Type ? for help. Commands must be C++ statements.
Enclose multiple statements between { }.
root [0] .L testfunc.C                                        
root [1] TF1 *testf1 = new TF1("testf1", testfunc, 3., 8., 0);
root [2] testf1 -> Draw();                                    
<TCanvas::MakeDefCanvas>: created default TCanvas with name c1
Error: G__CallFunc::SetArgArray() must be initialized with 
'G__CallFunc::SetFunc(G__ClassInfo* cls,char* fname,char* args,long*
poffset)' first
root [3] 

I don't understand this error. I've really tried to get this to work, but
with no avail. Can someone show me the error of my ways?

Thanks,
	-Kalen

-----------------------------------------------------------------
- Kalen Martens			 	     Ph:(416)-978-6632  -
- Dept. of Physics						-
- University of Toronto, Toronto, Canada			-
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