# color-coding a 2D plot

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Vahid on 27 Mar 2012
Hello everybody,
I am wondering how we can plot a 2D figure,x vs. y, which the amplitude of a given mathematical function, let say f(x,y) where e.g. f=sqrt(x.^2+y.^2), is encoded with colors in 2D plot as if max(f) is shown with e.g. blue color and min(f) with red color.
thank you so much, --V

Kevin Holst on 27 Mar 2012
unfortunately shading interp doesn't seem to work on contourf so here's an inelegant solution to your problem.
[x,y] = meshgrid(-10:0.1:10,-10:0.1:10); % just to get some x and y values
z = sqrt(x.^2 + y.^2);
surf(x,y,z)
set(gca,'cameraposition',[0 0 180]) % this essentially turns a 3d surface plot into a 2d plot
colormap(flipud(jet))
Vahid on 27 Mar 2012
nice solution! thanks again :-D

Kevin Holst on 27 Mar 2012
[x,y] = meshgrid(-10:0.1:10,-10:0.1:10); % just to get some x and y values
z = sqrt(x.^2 + y.^2);
contourf(x,y,z)
colormap(flipud(jet))
Is that what you're envisioning?

Vahid on 27 Mar 2012
Thanks Kevin! What I am looking for is very close to what your commands plot. I'd like to have a continuous color changing rather than using different colors, I mean contentiously changing from [0 0 1] to [1 0 0] which each three-element row vector is the RGB triple.