How can I loop into a matrix?

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saheed 2014-3-7

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评论： saheed 2014-3-8

采纳的回答： Mischa Kim

I have six values of E and v which are entries of Matrix s of the structure; s=[1/E -v/E 0; v/E 1/E 0; 0 0 2*(1+v)/E]

the six matrices of s formed are the entry into the matrix S; S=[s(1) s(2) s(3) s(4) s(5) s(6)]

How can I loop the values of E and v into the matrix s?

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Image Analyst 2014-3-7

Are E and V row matrices or column matrices? What do you think the size of little should be? And what about big S? Can you give a numerical example?

saheed 2014-3-7

E and v are coulmn matrices and the size of matrix s is 3 by 3 while size of matrix S is 3 by 18 since we have 6 s matrices in the column space of matrix S. for example,

s(i)=[1/E(i) -v(i)/E(i) 0; v(i)/E(i) 1/E(i) 0; 0 0 2*(1+v(i))/E(i)]

where i=1,2,..,6 for each value of E and v

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Answer 1

Mischa Kim 2014-3-7

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在 MATLAB Online 中打开

I assume you are trying to do something like

 for ii = 1:6
    S{ii} = [1 -v(ii) 0; v(ii) 1 0; 0 0 2*(1+v(ii))]/E(ii);
 end

Note that S is a cell array, so your first matrix (your s(1)) would be accessed as S{1}.

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Mischa Kim 2014-3-7

Yep, either way would work. My thinking was that Saheed wanted to access the inidividual matrix elements of S = [s(1) s(2) s(3) s(4) s(5) s(6)] with something that resembled that format.

saheed 2014-3-8

Thanks Patrick and Mischa. Patrick code works fine and suit my need.

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Answer 2

Patrik Ek 2014-3-7

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编辑：Patrik Ek 2014-3-7

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I think that you need to loop here, since Matlab do normally not implement any operations that you reuqests. I mean

[vector, 0; 0, vector]

gets the size 2 x length(vector)+1

try something like

s = [];
for k = 1:length(E)
    s_temp= [1/E(k) -v(k)/E(k) 0; v(k)/E(k) 1/E(k) 0; 0 0 2*(1+v(k))/E(k)];
    s = [s,s_temp];
end

I may have some syntax errors since the code is not tested, but I guess it should work. Of course you can also preallocate vectors and so as well to speed up the code, if that is necessary.

Good luck!