Hi Tony,
Thanks for reporting this interesting case. It is now fixed
in the development version in CVS.
Rene Brun
On Tue, 26 Feb 2002, Colley, Tony wrote:
>
> The following demonstrates a "minor" bug in TGraph:
>
> {
> Int_t i;
> Float_t x[1000];
> Float_t y[1000];
>
> for (i=0; i<1000; i++)
> {
> x[i] = 0.001*i;
> y[i] = 6.2831853*x[i];
> y[i] = sin(12*y[i]) + sin(17*y[i]) + sin(56*y[i]) + sin(74*y[i]);
> }
>
> TGraph *graph = new TGraph( 1000, x, y );
> graph->Draw("AL");
>
> printf(
> "\n\n===============================================================\n" );
> printf( "Right click on X axis and select SetRangeUser.\n" );
> printf( "Enter the range 0.387 to 0.389 and click OK.\n" );
> printf( "Move the cursor over one of the 3 points (at .387, .388, .389).\n"
> );
> printf( "Press down the left mouse button.\n" );
> printf( "When I do it, there are 6 extra boxes drawn\n" );
> printf( " (in addition to the three that should be drawn)\n" );
> printf( "===============================================================\n"
> );
> }
>
> (I've attached the same thing as tgdemo.C, in case that's easier to use than
> just cutting/pasting from this email)
>
> The y function was chosen arbitrarily. The bug appears for many other
> functions I tried.
>
> The bug is even more insidious when you significantly increase the number of
> data points graphed. When you zoom in close enough to begin seeing
> individual points, in addition to having many extra boxes, some boxes are
> apparently drawn too close to the edges because there is a wraparound effect
> (giving rectangles spanning the graph rather than little boxes around the
> points).
>
> I also noticed in the example I provided, if you don't zoom in quite so far,
> there are extra boxes drawn extending out of the left and right sides of the
> graph. These boxes seem to correspond to data points outside the graph
> clipping area but within the canvas clipping area. I'm not sure if I would
> classify this behaviour as a bug or a feature... it could be useful and may
> be intentional (i.e. a feature).
>
> Tony Colley
> ITT Industries A/CD
> Fort Wayne, IN USA
>
> Using ROOT 3.03/00, last updated from CVS on 18 Feb 2002, on RedHat Linux
> 7.2
>
>
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