MATLAB Answers

Salar
0

How do I add a value in ONE element of a matrix in a for loop?

Asked by Salar
on 30 May 2014
Latest activity Commented on by Salar
on 30 May 2014
Hello, let's say I have a matrix A = [1+x,1;2,5] so I want to have x to go from -20 to 20 with x~=0
then I would need to have A(i) matrices with i=40 . How do I do this on Matlab? I've been reading on internet on indexing and things like that, but I keep getting errors. I really appreciate you taking the time.
Sincerely,

  2 Comments

Does the second row (2,5) get repeated every time? Or does it become, let's say (you have 1 to 3)
A=[1, 1;
2,1;
3,1;
2,5]
Can you show an example of what you want the output to be?
Sure, let's say A = [1+x,1;2,5] , and for simplicity let's have x goes from -2 to 2 with and increment of one and x~=0, so output will look like =
A_1=[-1,1;2,5]
A_2=[0,1;2,5]
A_3=[2,1;2,5]
A_4=[3,1;2,5]

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2 Answers

Answer by Image Analyst
on 30 May 2014
 Accepted Answer

I show you two different methods in the loop below:
counter = 1;
A3D = [];
for x = -20 : 20
if x == 0
continue;
end
% Method #1: Load into a cell array.
caA{counter} = [1+x,1;2,5];
% Method #2: Load into a 3D regular, normal array
A3D = cat(3, A3D, [1+x,1;2,5]);
counter = counter + 1;
end
% Print to command window
celldisp(caA)
A3D

  1 Comment

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Answer by sst
on 30 May 2014
Edited by sst
on 30 May 2014

This should not require a for loop:
x = [-20:-1, 1:20].';
Amatrices = arrayfun(@(X) [1+X, 1; 2, 5], x, 'UniformOutput', false);

  1 Comment

That works, but do you know how to do it by a for loop?

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