bugGNU Octave - Bugs: bug #49872, Polar plot incorrect

 
 

bug #49872: Polar plot incorrect

Submitted by:  None
Submitted on:  Sat 17 Dec 2016 07:14:59 PM UTC  
 
Category: PlottingSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Incorrect Result
Status: Works For MeAssigned to: None
Originator Name: Arvind RaoOriginator Email: -unavailable-
Open/Closed: ClosedRelease: 4.2.0
Operating System: Any

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Sun 18 Dec 2016 10:40:43 AM UTC, comment #3:

Thanks Andreas. I see the problem was in the expression, not in Octave.

Anonymous
Sat 17 Dec 2016 08:22:31 PM UTC, comment #2:

You can also have a look here: http://josoansi.de/octave_plot_compare/compare_plot_demos_06.html

for the first demo of polar.m. As you can see Matlab does the same for negative RHO values as Octave.

Andreas Weber <andy1978>
Project Member
Sat 17 Dec 2016 08:17:37 PM UTC, comment #1:

Why do you think this is wrong?

I guess you want an output generated like "polar(phi, abs(U))", right?

Can you confirm that Matlab does behave differently as Octave for negative values of RHO?

Andreas Weber <andy1978>
Project Member
Sat 17 Dec 2016 07:14:59 PM UTC, original submission:

I am using Win 7. I wrote a simple program to plot a cardioid.

Program is below:

Plot is fine for b=1, 0.75, 0.5. When I change b to 1/3 or 0.25, the plot is wrong. The smaller lobe is expected to be to the left of the larger lobe instead of inside it. Plot for 0.25 is attached.

Anonymous

 

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Attached Files
file #39261:  hyper_cardioid_plot_bug.pdf added by None (7KiB - application/pdf - Plot for 0.25)

 

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  • -unavailable- added by rik5 (Updated the item)
  • -unavailable- added by andy1978 (Posted a comment)
  • -unavailable- added by None (Submitted the item)
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    Follow 4 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sun 18 Dec 2016 03:12:11 PM UTCrik5Open/ClosedOpen=>Closed
    Sat 17 Dec 2016 08:22:31 PM UTCandy1978StatusNone=>Works For Me
      Operating SystemMicrosoft Windows=>Any
    Sat 17 Dec 2016 07:14:59 PM UTCNoneAttached File-=>Added hyper_cardioid_plot_bug.pdf, #39261

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