How to vectorize For loop and array with indexing

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shahrizan jamaludin 2016-3-8

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评论： shahrizan jamaludin 2016-3-11

Hello, i want to vectorize the linecirc function below:

xout = zeros(nAngles,2); %360x2 size
yout = zeros(nAngles,2); %360x2 size
for i = 1:nAngles
[xout(i,:),yout(i,:)] = linecirc(slope(i),intercept(i),xp,yp,rp); %slope=intercept=1x360 size
end

before this, i tried to use arrayfun. unfortunately arrayfun is not faster than for loop. maybe indexing can make it faster. Thanks

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Star Strider 2016-3-8

What’s linecirc?

shahrizan jamaludin 2016-3-8

linecirc is a matlab function which to find intersections of circles and lines in Cartesian plane

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回答（1 个）

Matthew Eicholtz 2016-3-8

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Disclaimer: I do not have R2016a, so I cannot test the linecirc function.

But, if you already tried arrayfun and it was slower, I think the for-loop is going to be your fastest bet. Is there a reason (other than speed) that you want to vectorize the code? Sometimes a for-loop is the way to go.

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Matthew Eicholtz 2016-3-10

Ah, I thought linecirc was exclusive to R2016a, but I see now that it is in earlier versions. However, it requires the Mapping Toolbox, which I do not have, so I still cannot test it.

Vectorization is not always the best route if you do not need it. Hence my question about your motives.

shahrizan jamaludin 2016-3-11