can anyone explain what this piece of code do?

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Vinay Kumar 2014-10-15

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评论： Vinay Kumar 2014-10-16

[u,v] = pol2cart(center(:,3),8);
quiver(center(:,2),center(:,1),u,v,0.3,'g');

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Answer 1

Star Strider 2014-10-15

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The first line converts a (Nx3) matrix ‘center’ where ‘center(:,3)’ is a vector of angles, apparently defining vectors in those directions with a constant length of 8, and converts it to Cartesian coordinates.

The second line (using the quiver function) plots arrows with the first two columns of ‘center’ defining the the origins of the arrows and ‘u’ and ‘v’ (calculated in the first line) defining their directions and lengths.

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Star Strider 2014-10-16

在 MATLAB Online 中打开

My pleasure!

The assignment:

c = [];

sets variable ‘c’ equal to the empty matrix. It is useful if, for instance, you want to add other elements to it in a loop, for example:

for k = 1:10
    c = [c k];
end

It is preferable to do what is known as ‘preallocation’ rather than concatenation, but in some instances, preallocation is not possible and serial concatenation is the only way to create a variable array.

Vinay Kumar 2014-10-16