"Vector must be strictly increasing or strictly decreasing with no repeated values" error
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Hello,
I'm trying to use contour to represent some data, but I get this error.
Thank you in advance.
R_a=3;
N=100;
phi=linspace(0,2*pi,N);
rho= linspace(0,R_a,N);
r = randi([50 70],1,length(rho));
A=ones(length(rho)).*r;
[x_c,y_c] = pol2cart(phi,rho);
[Ro_tag, Phi_tag]=meshgrid(rho,phi);
contour(x_c,y_c,A);
4 Comments
Accepted Answer
Matt J
on 31 Aug 2020
Edited: Matt J
on 31 Aug 2020
Your meshgrid must be Cartesian:
R_a=3;
N=100;
[X,Y]=meshgrid( linspace(-R_a,+R_a, N) );
[Phi,Rho]=cart2pol(X,Y);
A= ... computaton based on Phi and Rho ...
contour(X,Y,A);
3 Comments
Matt J
on 31 Aug 2020
Edited: Matt J
on 31 Aug 2020
Very well, then I modify my answer to,
R_a=3;
N=100;
[X,Y]=meshgrid( linspace(-R_a,+R_a, N) );
A= ... computaton based on X and Y ...
contour(X,Y,A);
The point is, A needs to be sampled on a normal Cartesian meshgrid for the purposes of doing the contour plot. You cannot, as a starting point, set up your sample locations in polar coordinates because they will not remain monotonic when transformed by pol2cart().
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