MATLAB: Matrix neighbours chaning with iterations

changeiterationmatrixneighbour

Imagine I have matrix A=ones(5). I want to change center of the matrix to 17, A(3,3)=17; In next iteration I want to change all points that are next to this 20 to 5. i will have:
1 1 1 1 1
1 5 5 5 1
1 5 17 5 1
1 5 5 5 1
1 1 1 1 1
In next step i want to change all ones to 10. And so on…
10 10 10 10 10
10 5 5 5 10
10 5 17 5 10
10 5 5 5 10
10 10 10 10 10
Any idea how to do this to large matrix? How to adress only the neighbours but not the points "inside"?

Best Answer

  • [M,N]=size(A);
    center=size(A)/2+.5;
    [I,J]=ndgrid((1:M)-center(1), (1:N)-center(2));
    A(:) = 20-5*round(max(abs(I),abs(J)))