# Matlab contour labels for PDEs

• MATLAB
Is there a way that I can label contours for PDEs on Matlab? They have a few functions for drawing contours, e.g.

pdeplot(p,e,t,'xydata',u,'mesh','off','contour','on',' ...)

pdecont(p,t,u)
but they're unlabelled (what's the use!) I'm sure there's a way to label my contours if I could plot them in the first place, but searches yield none. I understand that there's a function

clabel(X,Y,Z)
but I can't think of how I can use it with given my data:

p(1,:) is the matrix containing the x-coordinates of u(:,1)
p(2,:) is the matrix containing the y-coordinates of u(:,1)
u(:,1) gives the solutions.

e.g. u(1) gives the solution at (p(1,1), p(2,2))

I tried the obvious,

clabel(p(1,:),p(2,:),u(:,1))
which doesn't work as far as it goes because I realised X and Y refers to a grid rather than the coordinates of certain elements of Z. Similarly, Z are the values at the points in the grid, rather at only certain, irregularly spaced coordinates.

Any help is appreciated, thanks in advance!

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Dr Transport
Gold Member
Try this......

cs = contour(X,Y,Z);
clabel(cs);

Yep, I've tried that. It doesn't work. I need to find a way to transform my x, y coordinates and PDE solution values into a strange form (X and Y must be at least 2x2 matrices).

Thanks nonetheless.

Hi..I have the same problem !!! I cant label the contours which come from the pdeplot(...) or pdecont(...).
Any solution ????

Hi, I'm sorry to disappoint you but I couldn't find a fix to this. I had to stick to a color map rather than contour labels, which is annoyingly inadequate.

pdeplot(...colormap, 'jet'...)

It's ok. Thank u for ur time.

Hey Guys

I would be grateful if you could have some time to look into my question, I am trying to do density plot (contour or surface or map)from a data file which has 3 columns.........the code below does not shows any errors, but also does not give any figure, I think may be the way I had added the extension manually(.csv......comma separated variables)...is there anyway to export my data in such extension file.....or if you have another way to plot data file by contour plot.........

Code:
data = csvread('my_file.csv');
x=data(:,1);
y=data(:,2);
z=data(:,3);
a=size(data);
b=a(:,1);
xlin=linspace(min(x),max(x),b);
ylin=linspace(min(y),max(y),b);
[X,Y]=meshgrid(xlin,ylin);
Z=griddata(x,y,z,X,Y);
mesh(X,Y,Z)
colorbar