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Constant Y Value, large number of points

Posted: Fri Apr 25, 2008 7:23 pm
by 9532498
I have a line (X/Y) series plot with several thousand data values. They all have the same Y value but differ in X. I should see a straight horizontal line, but instead I see series values all over the place. The Y axis is labelled with the correct Y-value with Y Minimum and Y Maximum being the same. All the labels on the Y-Axis are labelled the same (correct Y value). Is this a bug? Should I be setting some atribute of the chart so as the get the correct display?

When I change the Y Minimum and Maximum manually so that the correct (constant) Y value falls between the min and max, I see the data displayed correctly as a straight horizontal line.

Posted: Mon Apr 28, 2008 8:20 am
by yeray
Hi nbp,

I haven't been able to reproduce the problem here with v8.0.0.3. Please, could you send us a simple example project we can run "as-is" to reproduce it here?
You can either post your files at news://www.steema.net/steema.public.attachments newsgroup or at our upload page.

And also, could you please tell us what exactly TeeChart version are you using?

Posted: Mon Apr 28, 2008 1:57 pm
by 9526464
Quick suggestion from a passer-by: maybe the values are not exactly the same and you are seeing quantization noise? Are the values mathematically equal or just really close? Try increasing the number of digits on the Y-scale - it might make it obvious what is going on. From my experience, if all your values are exactly the same, TeeChart does not show a min and a max for that axis - it shows a single number in the middle of the scale.

Posted: Mon Apr 28, 2008 3:57 pm
by 9532498
Thanks! That's exactly what it was. I changed the number of decimal points on the Y-Axis and realized there were very small differences in the values.

Posted: Tue Apr 29, 2008 7:42 am
by yeray
Hi nbp,

I'm glad to read that you solved it!