How to create a matrix of size N×N that has ones in the border and zeros inside?

Create a matrix of size N×N that has ones in the border and zeros inside.

For example, if N=3 the matrix can be created with

>> A=ones(3,3);

 A(2,2)=0
A =
     1     1     1
     1     0     1
     1     1     1

Make this construction depend on N and work for any positive integer N≥2.

Answer 1

[KL]

function A = oneZeroMatrix(N)
A = zeros(N);
A([1 end],:)=1;
A(:,[1 end])=1;

end

%  and then
N = 5;
A = oneZeroMatrix(N);

[Carolyn]

Shouldn't it be [1:end] inside the "A" matrix instead of [1 end]?

[Walter Roberson]

@Carolyn

Let us experiment:

N = 5;
A = oneZeroMatrix_original(N)

A = 5×5

1 1 1 1 1 1 0 0 0 1 1 0 0 0 1 1 0 0 0 1 1 1 1 1 1

A = oneZeroMatrix_modified(N)

A = 5×5

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

function A = oneZeroMatrix_original(N)
A = zeros(N);
A([1 end],:)=1;
A(:,[1 end])=1;
end

function A = oneZeroMatrix_modified(N)
A = zeros(N);
A([1:end],:)=1;
A(:,[1:end])=1;
end

Answer 2

[Stephen23]

M = ones(5);
M(2:end-1,2:end-1) = 0

M = 5×5

1 1 1 1 1 1 0 0 0 1 1 0 0 0 1 1 0 0 0 1 1 1 1 1 1