Steema Central

I have a polar plot, which can show either square meter or dB over 1 sqr m.
The later uses log10 scale!

When I change the scale in dB mode (plot is, of course, using linear scales) everything works fine.
If I have set the boundaries to 0 and 5 (dB) my curve says 3.9 dB.
Changing the lower boundary still keeps the curve at 3.9.

Switching to log mode (converting data to sqr m) the scale goes from 1 to 3.16 sqr m. But the curve is now equivalent to 4.6 dB! (no propper scale or grid is available in log mode, unfortunately )
Changing the lower boundary to 2 sqr m moves the curve down to 3.2 db.
(and might actually be inverted!)

The data is correctly converted back and forth (db <-> sqr m), but plotting seems to have a problem.
If the lower boundary is set too high, the plot will be 'inverted'. Data being plotted somewhere 180 deg. rotated. The scalcurve is rather steep on that side!
Not so in dB mode. The curve just simply disappears.

Auto scaling does find the propper values, but they are no good, if the plot itself does not work.

I am using v. 7.12, which I believe is the latest we got license for.
I am using Delphi 6 with all updates.

Hi ole,

Could you please send us a simple example project we can run "as-is" to reproduce the problem here? You can either post your files at news://www.steema.net/steema.public.attachments newsgroup or at our upload page.

Thanks in advance.

I have uploaded a zip file (PolarDemo.zip) containing a demo (exe and all source) of the problem.

The application places different values in the four quadrants. 316, 10, 31.6 and 100.
The chart has just been brutally copied from my actual application with only little adjustment for this demo.

The upper and lower boundaries are set to 316 and 3.16 respectively.

The up/down controls adjust the limits by approx. 1 dB.

Notice what happens to data plots, when the lower limit increases.
All four quadrants in fact if you increase minimum far enough!

Then try doing the same in linear mode by unchecking "Log scale".

There is no inteligence in the limits, so you will get a warning from the chart, if you go too far.

No feedback on this so far

Does that mean:

• That You can not reproduce the error?
  That the bug has been fixed in some later version ?
  That You have not received the files yet, or can not read them ?

Hi walker1,

Sorry for the delayed reply.

We could identify this as a bug (TV52012929) but we can not give an estimate date for this being fixed. Obviously, logarithmic axes don't plot correctly with polar series under some circumstances (when axis minimum is greater than zero).