how to generate matrix with any size in same pattern

Question

yibin 2013-4-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/73045-how-to-generate-matrix-with-any-size-in-same-pattern

编辑： Andrei Bobrov 2019-12-12

 -2     1     0     0     0     0
  -2     1     0     0     0
   1    -2     1     0     0
   0     1    -2     1     0
   0     0     1    -2     1
   0     0     0     1    -2

i need to generate a matrix with pattern like this. how to write a script that the required pattern

for example, if i need 5*5 matrix with the required pattern it will be like this

 -2     1     0     0     0     
  -2     1     0     0     
   1    -2     1     0     
   0     1    -2     1
   0     0     1    -2

or i need 7*7 matrix

 -2     1     0     0     0     0     0
  -2     1     0     0     0     0
   1    -2     1     0     0     0
   0     1    -2     1     0     0
   0     0     1    -2     1     0
   0     0     0     1    -2     1
   0     0     0     0     1    -2

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per isakson 2013-4-22

Homework?

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Answer 1

Walter Roberson 2013-4-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/73045-how-to-generate-matrix-with-any-size-in-same-pattern#answer_83027

See http://www.mathworks.com/help/matlab/ref/diag.html

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Answer 2

Andrei Bobrov 2013-4-22

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https://ww2.mathworks.cn/matlabcentral/answers/73045-how-to-generate-matrix-with-any-size-in-same-pattern#answer_83034

编辑：Andrei Bobrov 2019-12-12

在 MATLAB Online 中打开

n = 5;
out = full(spdiags(ones(n,1)*[1 -2 1],-1:1,n,n));

or

out = zeros(n);
out([2:n+1:end,n+1:n+1:end]) = 1;
out(1:n+1:end) = -2;

or

out = zeros(n);
z = diag(true(n-1,1),-1);
out(z | z') = 1;
out(eye(n) > 0) = -2;

and (after 6.5 years ;)

n = 10;
out = toeplitz([-2 1 zeros(1,n-2)]);

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Answer 3

Bandar 2019-12-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/73045-how-to-generate-matrix-with-any-size-in-same-pattern#answer_406043

在 MATLAB Online 中打开

n=5;
v =-2*ones(1,n);
p =ones(1,n-1);
B =diag(v);
C =diag(p,1);
D =diag(p,-1);
A=B+C+D

The result is

A =
    -2     1     0     0     0
     1    -2     1     0     0
     0     1    -2     1     0
     0     0     1    -2     1
     0     0     0     1    -2