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Problems with ellipse object

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  Problems with ellipse object Francisco Pontiga <pontiga@us.es> - 2017-04-18 02:53 -0700
    Re: Problems with ellipse object Karl Ratzsch <mail.kfr@gmx.net> - 2017-04-18 12:41 +0200
    Re: Problems with ellipse object Karl Ratzsch <mail.kfr@gmx.net> - 2017-04-18 13:12 +0200
      Re: Problems with ellipse object Karl Ratzsch <mail.kfr@gmx.net> - 2017-04-18 21:02 +0200
        Re: Problems with ellipse object Karl Ratzsch <mail.kfr@gmx.net> - 2017-04-21 09:57 +0200
    Re: Problems with ellipse object Francisco Pontiga <pontiga@us.es> - 2017-04-18 04:59 -0700

#3623 — Problems with ellipse object

Hello,

I would appreciate any help with these two problems. I am trying to draw an ellipse inside a splot at a convenient place, but I found the following problems (or bugs?)

Here is a short sample of a test file:

reset
set terminal windows color enhanced 
set pm3d
set view map
set palette color
unset surface
set object 1 ellipse at 0.0,0.0 size 0.5,0.5 angle 0 front fillcolor rgbcolor "white"
splot [-2:2][-2:2] x**2+y**2 notitle with lines

I would expect the ellipse to be drawn with its center at the origin (coordinates (0.0,0.0)) but instead, it is drawn with its center at (0.0,2.0). Why? I have tried writing explicitly "at first 0.0,first 0.0" , but the result is identical. Indeed, I must write " at 0.0,-2.0" in order to have the ellipse drawn with its center at the origin.

Things become worse when I try to use a log scale for the z-axis. If I write

reset
set terminal windows color enhanced 
set pm3d
set view map
set palette color
unset surface
set log z
set object 1 ellipse at 0.0,0.0 size 0.5,0.5 angle 0 front fillcolor rgbcolor "white"
splot [-2:2][-2:2] x**2+y**2 notitle with lines

I got the following error: "ellipse has z coord of 0; must be above 0 for log scale! "

How can I modify the z coordinate of the ellipse?

Thank you in advance for any help.

Francisco

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#3624

Am 18.04.2017 um 11:53 schrieb Francisco Pontiga:

> set terminal windows color enhanced 
> set pm3d
> set view map
> set palette color
> unset surface
> set object 1 ellipse at 0.0,0.0 size 0.5,0.5 angle 0 front fillcolor rgbcolor "white"
> splot [-2:2][-2:2] x**2+y**2 notitle with lines
> 
> I would expect the ellipse to be drawn with its center at the origin (coordinates (0.0,0.0)) but instead, it is drawn with its center at (0.0,2.0). Why? I have tried writing explicitly "at first 0.0,first 0.0" , but the result is identical. Indeed, I must write " at 0.0,-2.0" in order to have the ellipse drawn with its center at the origin.

I only see that problem with version 4.6pl5 and older, but not with
4.6pl6 or any 5.0 release I tried. Must be some long fixed bug.

Can you upgrade?

https://sourceforge.net/projects/gnuplot/files/gnuplot/5.0.6/

  Karl

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#3625

Am 18.04.2017 um 11:53 schrieb Francisco Pontiga:
> Things become worse when I try to use a log scale for the z-axis. If I write

> set log z
> set object 1 ellipse at 0.0,0.0 size 0.5,0.5 angle 0 front fillcolor rgbcolor "white"
> splot [-2:2][-2:2] x**2+y**2 notitle with lines
> 
> I got the following error: "ellipse has z coord of 0; must be above 0 for log scale! "
> 
> How can I modify the z coordinate of the ellipse?

Well, you just can give a bogus positive z coordinate :

  set view map
  set log z
  set object 1 ellipse at 0.0,0.0,1 size 0.5,0.5,1 angle 0 front
  splot [-2:2][-2:2] x**2+y**2 notitle with lines

,  but the error (message) is of course nonsense. File a bug report
about it on https://sourceforge.net/p/gnuplot/bugs ?

  Karl

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#3627

Am 18.04.2017 um 13:12 schrieb Karl Ratzsch:
> Well, you just can give a bogus positive z coordinate :
> 
>   set view map
>   set log z
>   set object 1 ellipse at 0.0,0.0,1 size 0.5,0.5,1 angle 0 front
>   splot [-2:2][-2:2] x**2+y**2 notitle with lines

This is of course not intended to work, really, and the trick falls
to the side with latest cvs of both the stable and development tree,
most likely due to the latest changes (2017-04-10) in src/graphics.c.

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#3631

Am 18.04.2017 um 21:02 schrieb Karl Ratzsch:
> Am 18.04.2017 um 13:12 schrieb Karl Ratzsch:
>> Well, you just can give a bogus positive z coordinate :
>>
>>   set view map
>>   set log z
>>   set object 1 ellipse at 0.0,0.0,1 size 0.5,0.5,1 angle 0 front
>>   splot [-2:2][-2:2] x**2+y**2 notitle with lines
> 
> This is of course not intended to work, really, and the trick falls
> to the side with latest cvs of both the stable and development tree,
> most likely due to the latest changes (2017-04-10) in src/graphics.c.

And as of 2017-04-18, map mode disregards the z coordinate for
placing objects. Thanks, Ethan!

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#3626

Thank you very much for your advise!

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