Re: contour plotting with

[Mishal Mohanlal]

Hi Markus

Thank you for your help.

Sorry for some reason I cannot reply through the forum.

Just a note, I found that in some instances with huge data Octave will stop responding when using "contourf"  and the method which you proposed, it seems that the NaN uses additional resources when compared to an actual number. It also sometimes cannot compute the correct contours and messes up the data.

I found that using the "fill" function works well and is less intensive, especially with complex regions.

Kind regards

Mishal Mohanlal 

On Wed, Jun 3, 2020 at 11:58 AM "Markus Mützel" <markus.muetzel@gmx.de> wrote:

Am 03. Juni 2020 um 11:51 Uhr schrieb mishal0488:
> Hi Markus
>
> Thanks for the suggestion.
>
> I managed t get it to work using a number however using NaN does not plot anything. Do you perhaps any further guidance?

NaN works for me with Octave 5.2 (adapted from "demo contour 1"):

clf (figure (1));
colormap ("default");
[x, y, z] = peaks ();
contour (x, y, z);
title ({"contour() plot (isolines of constant Z)"; "Z = peaks()"});

clf (figure (2));
colormap ("default");
z(abs(x) <= 0.5) = NaN;
contour (x, y, z);
title ({"contour() plot (isolines of constant Z)"; "without stripe at center"});


HTH,
Markus