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How do I create a matrix surrounding the center element?

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J AI 2019 年 11 月 4 日
編集済み: Bhaskar R 2019 年 11 月 4 日
I want to create a matrix (n by n, n being odd) that has its central element fixed, and its surrounding elements increasing/decreasing by some constant value. For example:
where my center element is 0 and the surrounding elements are decrementing by 0.1. I am pretty much blank from where to start exactly. Your time and help is highly appreciated.


Shubham Gupta
Shubham Gupta 2019 年 11 月 4 日
n = 5;
A = zeros(n);
[r,c] = find(A==0);
sub = [r,c]-(n+1)/2;
for i = 1:(n-1)/2
ind = find((sub(:,1)==-i&sub(:,2)>=-i&sub(:,2)<=i)|(sub(:,1)==i&sub(:,2)>=-i&sub(:,2)<=i)|(sub(:,2)==-i&sub(:,1)>=-i&sub(:,1)<=i)|(sub(:,2)==i&sub(:,1)>=-i&sub(:,1)<=i));
A(ind) = -0.1*i;
Let me know if you have doubts !
  1 件のコメント
J AI 2019 年 11 月 4 日
Thanks a lot!


その他の回答 (1 件)

Bhaskar R
Bhaskar R 2019 年 11 月 4 日
編集済み: Bhaskar R 2019 年 11 月 4 日
% works for only odd numbers as your requirement
n = 5; % matrix size
r = (n-1)/2; % surrounding rows
x = zeros(n); % array initialization
c = r-1:-1:0;
% assigning values
for i = 1:r
x([1+c(i), end-c(i)], :) = -i/10;
x(:,[1+c(i), end-c(i)]) = -i/10;
x % final matrix

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