Find submatrix given two corners of matrix

Given a matrix

{'A'} {'B'} {'C'} {'D'} {'E'}

{'F'} {'G'} {'H'} {'I'} {'J'}

{'K'} {'L'} {'M'} {'N'} {'O'}

{'P'} {'Q'} {'R'} {'S'} {'T'}

{'U'} {'V'} {'W'} {'X'} {'Y'}

we can get that using

square=cell(5);
alpha='A':'Y';
for i=1:25
    square{i}=alpha(i)
end
square=square'

using the matrix either

0 0 0 0 0

0 1 0 0 0

0 0 0 0 0

0 0 0 0 1

0 0 0 0 0

or

0 0 0 0 0

0 0 0 0 1

0 0 0 0 0

0 1 0 0 0

0 0 0 0 0

for corners

extract

{'G'} {'H'} {'I'} {'J'}

{'L'} {'M'} {'N'} {'O'}

{'Q'} {'R'} {'S'} {'T'}

Answer 1

[GreenEye]

For anyone in the future, I solved it. Here is the code. Replace S and A with any letters

%this part constructs the matrix
square=cell(5);
alpha='A':'Y';
for i=1:25
    square{i}=alpha(i);
end
square=square';

[row,col]=find(ismember(reshape(alpha,5,[])',['S' 'A'])==1); %find the corners
%of submatrix given two letters
submat=square(row(1):row(2),col(1):col(2)); %find indices of corners and construct a submatrix
if isempty(submat) %if matrix is empty, reverse rows
    submat=square(row(2):row(1),col(1):col(2));
end
disp(submat)