# How do you create a surf plot in cylindrical coordinates?

96 Ansichten (letzte 30 Tage)
Jeremy Pearson am 17 Nov. 2012
In general, the syntax for a surf plot is surf(X,Y,Z). I have u = F(r,z). I'd like to do surface plots of u for multiple cross sections at z = h1, h2, h3, etc. Is there a simple way to create a surf plot in cylindrical coordinates, i.e., something that would be analagous to the syntax: surf(r,phi,u) where u = u(r,h1)?
##### 0 Kommentare-2 ältere Kommentare anzeigen-2 ältere Kommentare ausblenden

Melden Sie sich an, um zu kommentieren.

### Akzeptierte Antwort

Jonathan Epperl am 19 Nov. 2012
Or even easier, remember that you're not forced to put just one variable X in the first argument of surf, all you need is a parametrization. So in your case, assume you have vectors r and phi. Then make them into a grid, obtain a matrix with z-values using your function F and just plot:
[R PHI] = meshgrid(r,phi);
Z = F(R,PHI); % which assumes your function is vectorized
surf(R.*cos(PHI), R.*sin(PHI), Z);
##### 1 Kommentar-1 ältere Kommentare anzeigen-1 ältere Kommentare ausblenden
Jeremy Pearson am 19 Nov. 2012
Jonathan,
Works great! I had to modify the code a little bit to get it to work since F is a function of r and z and not r and phi, but your tip put me in the right direction. This is the code I entered:
>> [r,theta] = meshgrid(linspace(0,0.7,30),linspace(0,2*pi,30));
>> flux = F(r,meshgrid(linspace(0.4,0.4,30))); % new meshgrid defines z
>> surf(r.*cos(theta),r.*sin(theta),flux);
I may have not had to create and extra meshgrid and define everything in linspace but I just fiddled with it until it worked.
Jeremy

Melden Sie sich an, um zu kommentieren.

### Weitere Antworten (2)

Matt J am 17 Nov. 2012
Use TriScatteredInterp to interpolate your data onto a cartesian grid. Then plot using SURF as usual.
##### 0 Kommentare-2 ältere Kommentare anzeigen-2 ältere Kommentare ausblenden

Melden Sie sich an, um zu kommentieren.

Teja Muppirala am 19 Nov. 2012
You can use POL2CART to convert the data from r/theta to x/y and then call SURF.
[R,TH] = ndgrid(0:0.1:5,linspace(0,2*pi,41));
F = @(r,th) sin(th).*sinc(1+r);
Z = F(R,TH);
[X,Y] = pol2cart(TH,R);
surf(X,Y,Z);
##### 0 Kommentare-2 ältere Kommentare anzeigen-2 ältere Kommentare ausblenden

Melden Sie sich an, um zu kommentieren.

### Kategorien

Mehr zu Surface and Mesh Plots finden Sie in Help Center und File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by