Indexing issue- using negative values in for loop calculations.

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Shrishti Yadav
Shrishti Yadav 2021-10-30
评论： Shrishti Yadav 2021-10-30
I would like to store the values Zx and Zy from the code below in Z but not sure how.
clc;
u = 4
Z = zeros(u*u,1);
cx = 1;
cy = 1;
r = 3;
for j = 1:(u*u)
for x = -u:u
for y = -u:u
theta = atan2((y-cy) ,(x-cx));
Zx = cx-r*cos(theta)
Zy = cy - r*sin(theta)
Z(j,1) = (Zx);
Z(j,2) = (Zy);
end
end
end

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DGM
DGM 2021-10-30
Ran in:
It's not clear why you're overwriting your results and then repeating the process 16 times anyway. If you want Z for all x and all y, then the outer loop doesn't do anything.
u = 4;
Z = zeros(u*u,1);
cx = 1;
cy = 1;
r = 3;
x = -u:u;
y = (-u:u).';
theta = atan2((y-cy) ,(x-cx));
Zx = cx - r*cos(theta)
Zx = 9×9
3.1213 2.8741 2.5435 2.1142 1.5883 1.0000 0.4117 -0.1142 -0.5435 3.3426 3.1213 2.8000 2.3416 1.7276 1.0000 0.2724 -0.3416 -0.8000 3.5725 3.4000 3.1213 2.6641 1.9487 1.0000 0.0513 -0.6641 -1.1213 3.7854 3.6833 3.4962 3.1213 2.3416 1.0000 -0.3416 -1.1213 -1.4962 3.9417 3.9104 3.8460 3.6833 3.1213 1.0000 -1.1213 -1.6833 -1.8460 4.0000 4.0000 4.0000 4.0000 4.0000 -2.0000 -2.0000 -2.0000 -2.0000 3.9417 3.9104 3.8460 3.6833 3.1213 1.0000 -1.1213 -1.6833 -1.8460 3.7854 3.6833 3.4962 3.1213 2.3416 1.0000 -0.3416 -1.1213 -1.4962 3.5725 3.4000 3.1213 2.6641 1.9487 1.0000 0.0513 -0.6641 -1.1213
Zy = cy - r*sin(theta)
Zy = 9×9
3.1213 3.3426 3.5725 3.7854 3.9417 4.0000 3.9417 3.7854 3.5725 2.8741 3.1213 3.4000 3.6833 3.9104 4.0000 3.9104 3.6833 3.4000 2.5435 2.8000 3.1213 3.4962 3.8460 4.0000 3.8460 3.4962 3.1213 2.1142 2.3416 2.6641 3.1213 3.6833 4.0000 3.6833 3.1213 2.6641 1.5883 1.7276 1.9487 2.3416 3.1213 4.0000 3.1213 2.3416 1.9487 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 0.4117 0.2724 0.0513 -0.3416 -1.1213 -2.0000 -1.1213 -0.3416 0.0513 -0.1142 -0.3416 -0.6641 -1.1213 -1.6833 -2.0000 -1.6833 -1.1213 -0.6641 -0.5435 -0.8000 -1.1213 -1.4962 -1.8460 -2.0000 -1.8460 -1.4962 -1.1213
If you want Zx and Zy to be reshaped as column vectors, figure out how you want them reshaped:
Z = [Zx(:) Zy(:)]
Z = 81×2
3.1213 3.1213 3.3426 2.8741 3.5725 2.5435 3.7854 2.1142 3.9417 1.5883 4.0000 1.0000 3.9417 0.4117 3.7854 -0.1142 3.5725 -0.5435 2.8741 3.3426

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