"For" loop output storage

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John Paul Donlon
John Paul Donlon on 7 Nov 2012
I have four sets of 10 points. I need to generate every possible coordinate system resulting from a combination of four points (one from each set). How can I use nested for loops to calculate and save each coordinate system? Here is what I have so far. Thank you in advance.
% The four sets of 10 points are stored in rows 1:10, with three columns per
% set (x, y, z), of the array 'array'
for a = 1:10
for b = 1:10
for c = 1:10
for d = 1:10
p1 = array(a,1:3);
p2 = array(b,4:6);
p3 = array(c,7:9);
p4 = array(d,10:12);
% Code to calculate coordinate system 'cs' defined by column
% vectors U, V, and W
cs = [U,V,W];
% This is where I need help: I need to save each 'cs' such that I
% have a list of coordinate systems; for example (r0, r1, r2,
% r3,...), where rN = [U,V,W]
end
end
end
end

Accepted Answer

Jonathan Epperl
Jonathan Epperl on 7 Nov 2012
Use a cell array, that is not the most elegant or efficient way, but definitely the quickest fix:
Csystems = cell(10^4,1); % You'll have 10^4 different coord systems
for a = ...
% your code
cs = [U,V,W];
Csystems{1+ (10.^(0:3))*([d c b a]-1)'} = cs;
end
end
end
Now you can access your coordinate systems as
Csystems{1}
Csystems{2}
% ...
Csystems{10^4}
  1 Comment
John Paul Donlon
John Paul Donlon on 7 Nov 2012
Edited: John Paul Donlon on 7 Nov 2012
Thank you, Jonathan; that works.

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More Answers (1)

David Barry
David Barry on 7 Nov 2012
John, you could define a variable before the first for loop such as counter = 1; and then use this to index cs in the inner loop. Obviously don't forget to add 1 after each iteration.
  1 Comment
John Paul Donlon
John Paul Donlon on 7 Nov 2012
David,
Thank you for your answer; how do I index 'cs'?
count = 1
...
cs(count) = [U,V,W];
count = count + 1;

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