How can I modify values of eye

I am trying to code huckles determinant, and was able to get the matrix for cyclic hydrocarbons and lineal ones, however, I have not been able to do it for chains of carbons with substituents like (carbon 1, has 1 ch3 substituent)... I tried changing the values specifically of the eye matrix, but it just keeps on adding a two for every value instead of only the 6th and 7th value of a 5 carbon chain. I tried using A(r,c) = 2.... sorry the inputs are in spanish... Please help if you can!

disp('Hueckels determinante ')
pause(1)
s = menu('Hidrocarburos','Ciclicos', 'Lineales', 'Substituidos');
c = input('Cantidad de carbonos del Hidrobarburo ');
switch s
    case 1
        A = -eye(c);
        A(1,c) = 1;
        A(c,1) = 1;
        v = ones(1,c-1);
        A(logical(diag(v,1)))= 1;
        A(logical(diag(v,-1)))= 1
    case 2
        A = -eye(c);
        v = ones(1,c-1);
        A(logical(diag(v,1)))= 1;
        A(logical(diag(v,-1)))= 1
    case 3
        d = input('Cantidad de susbtituyentes ' );
        for K = 1:d
           disp(['En cual carbono: ' ,num2str(K),])
            m(K) = input(' ');
        end
        c = input('Cantidad de carbonos del Hidrobarburo ');
        x = ((c+1):(c+d));
        A = -eye(c);
        v = ones(1,c-1);
        A(logical(diag(v,1)))= 1;
        A(logical(diag(v,-1)))= 1
        A(m,x) = 2
        A(x,m) = 2
end

[Jan]

The technical terms "huckles determinant", "cyclic hydrocarbons", etc. are confusing only. Remember that Matlab does not know its meaning and in consequence these details are not required for a working solution also. Prefer to concentrate on the problem: Which part of the code does not work as expected? Which result do you get and what do you want instead? An explicit example would be useful.

[Stephen23]

Jhanna Ramirez Medina's "Answer" moved here:

case 3
        d = input('Cantidad de susbtituyentes ' );
        for K = 1:d
           disp(['En cual carbono: ' ,num2str(K),])
            m(K) = input(' ');
        end
        c = input('Cantidad de carbonos del Hidrobarburo ');
        x = ((c+1):(c+d));
        A = -eye(c);
        v = ones(1,c-1);
        A(logical(diag(v,1)))= 1;
        A(logical(diag(v,-1)))= 1
        A(m,x) = 1
        A(x,m) = 1

My problem is with this case specifically, I have my matrix -eye(c+d) which is the amount in total I want to input in the end, so I try to modify the diagonal (A(logical(diag(v,1)))= 1) to only change the values until c, which takes it from v = ones(1,c-1) here, what gives me is a matrix that misplaces the (1) ones to other places...... Also, I want to modify the -eye matrix introducing specific values like changing a zero in colunm 1 and row 6 to 1, that dependent on the input (d) and the for loop (m). so it should give me something like this:

[Jhanna Ramirez Medina]

I tried offset to limit the diagonals (1) and (-1), but it shows an error saying index matrix doesn't match, or exceeds dimension.

[Jan]

Please post the code and the complete error message. I still do not understand, what the problem is.

The screenshot is not really clear due to the "-x".

[Guillaume]

@Jhanna, To make it easier to understand what you, give us (using valid matlab syntax) and example of input and the desired output from that.

[Jhanna Ramirez Medina]

Alright, I will keep it in mind next time. Thank you!

Answer 1

[Jhanna Ramirez Medina]

Do no worry, I was able to make it work. Thanks though, I appreciate it!