using surf and pol2cart on matrix

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prrrrr 2020-6-25

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评论： Star Strider 2020-6-26

hello i have a 512x1000 matzrix

the coordinates are there divided into lines (x) as radius and columns (y) as angles. To each point in the matrix belongs a value (z).

How do I get the polar coordinates into cartesian coordinates (pol2cart). And can it plot at the end (with surf?)?

I would like to get in principle from my picture A the picture B

EDIT Forgot Code Example:

angles = (0:pi/8:2*pi)';
radii = 1:10;
[X, Y] = pol2cart(angles, radii)

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Adam Danz 2020-6-25

Are the angles vector and the radii vector supposed to be different lengths?

How do those values plot a circle?

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Answer 1

Star Strider 2020-6-25

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编辑：Star Strider 2020-6-25

在 MATLAB Online 中打开

The matrix you have is actually the ‘Z’ matrix. You need to create separate radius and angle matrices of the same size (use ndgrid or meshgrid for that, and be aware that their outputs are not the same), then use all three of those matrices as arguments to pol2cart. You will likely need to experiment a bit.

See: Plotting an exponential exp(-x), in 3D? for an example.

EDIT — (25 Jun 2020 at 23:17)

Using code example, try something like this:

Z = rand(512,1000);                                 % Create 'Z'
angles = linspace(0, 2*pi, size(Z,2));
radii = linspace(1, 10, size(Z,1));
[A, R] = meshgrid(angles, radii);
[X, Y, Z] = pol2cart(A, R, Z);
figure
surf(X, Y, Z)
shading('interp')
grid on