How can I put the outputs of for loop into a matrix?

Question

Eray Bozoglu 2020-11-30

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/669803-how-can-i-put-the-outputs-of-for-loop-into-a-matrix

评论： Eray Bozoglu 2020-12-1

采纳的回答： John D'Errico

Hey i am new to matlab and need help with storing answer of my for loop into a matrix can anyone help ?

my aim is having (n x n) matrix. thanks a lot

n=input('please enter n>');

for j=1:n

for i=1:n

a=(5*(i/n))+(8*(j/n));

end

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Eray Bozoglu 2020-11-30

edited the post im trying to have (n x n) matrix. with the current code if i plug 2 i can have 4 out put. such as

a b c d

i want to have them stored as [a b ; c d]

so for bigger n i can have better overview and use it in another script with defining it as a matrix.

Rik 2020-11-30

You are still overwriting a in every iteration.

Did you do a basic Matlab tutorial?

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Answer 1

John D'Errico 2020-11-30

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/669803-how-can-i-put-the-outputs-of-for-loop-into-a-matrix#answer_560803

编辑：John D'Errico 2020-11-30

在 MATLAB Online 中打开

First, don't use loops at all. For example, with n==3...

n = 3;
ind = 1:n;
a = ind.'*5/n + ind*8/n
a = 3×3
    4.3333    7.0000    9.6667
    6.0000    8.6667   11.3333
    7.6667   10.3333   13.0000
●

Since this is probably homework, and a loop is required, while I tend not to do homework assignments, you came pretty close. You made only two mistakes. First, you did not preallocate a, which is important for speed, but not crucial. It would still run without that line. Second, you are stuffing the elements as created into a(i,j). So you need to write it that way.

n = 3;
a = zeros(n); % preallocate arrays
for i = 1:n
    for j = 1:n
        a(i,j) = (5*(i/n))+(8*(j/n));
    end
end
a
a = 3×3
    4.3333    7.0000    9.6667
    6.0000    8.6667   11.3333
    7.6667   10.3333   13.0000
●