Create a loop for this matrix

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Rayden Plasma 2021-6-4

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/848110-create-a-loop-for-this-matrix

评论： Rayden Plasma 2021-6-4

采纳的回答： David Fletcher

1 -1 0 0 0 ...

-1 2 -1 0 0 ...

0 -1 2 -1 0 ...

0 0 -1 2 -1 ...

0 0 0 -1 2 ...

As you can see, this can go on forever, I and would like to find a way to write loop for a dynamic matrix where this just keeps going unitl a certain number 'N'

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David Fletcher 2021-6-4

编辑：David Fletcher 2021-6-4

I think they are asking what the end of the final row should be - I would guess [zeros(N-2,1) -1 1]

Rayden Plasma 2021-6-4

correct

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Answer 1

David Fletcher 2021-6-4

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/848110-create-a-loop-for-this-matrix#answer_716925

编辑：David Fletcher 2021-6-4

在 MATLAB Online 中打开

Just writing something with a loop on the fly (and I stress this is neither robust, nor particularly efficient), but it may be something you can work on in the absence of better answers

clear;
N=10;
base=[1 -1 0;-1 2 -1;0 -1 1];
spliceL=0;
spliceR=N-3;
reform(1,:)=[zeros(1,spliceL) base(1,:) zeros(1,spliceR)];
for iter=2:N-1
    reform(iter,:)=[zeros(1,spliceL) base(2,:) zeros(1,spliceR)];
    spliceL=spliceL+1;
    spliceR=spliceR-1;
end
reform(end+1,:)=[zeros(1,spliceL) base(3,end-1:end) zeros(1,spliceR-1)];
reform
reform = 10×10
     1    -1     0     0     0     0     0     0     0     0
    -1     2    -1     0     0     0     0     0     0     0
     0    -1     2    -1     0     0     0     0     0     0
     0     0    -1     2    -1     0     0     0     0     0
     0     0     0    -1     2    -1     0     0     0     0
     0     0     0     0    -1     2    -1     0     0     0
     0     0     0     0     0    -1     2    -1     0     0
     0     0     0     0     0     0    -1     2    -1     0
     0     0     0     0     0     0     0    -1     2    -1
     0     0     0     0     0     0     0     0    -1     1