Index exceeds matrix dimensions-when finding inverse of binary matrix,A

Hi.. I am using Galois field to find the inverse of a binary matrix, A and here is my program: _________________________________________________________________

H_matrix=input('Insert the H-matrix:');

H=H_matrix;
[num_rows num_cols]=size(H)

A=H(1:num_rows, 1:num_rows)
B=H(1:num_rows, num_rows+1:end)

% We need to find the inverse of matrix A..
% We set A in the Galois field so as to calculate the inverse using the
% inbuilt matlab function inv()
disp('Setting Matrix A in Galois field');
A_GF=gf(A)
disp('The inverse of matrix A in Galois field is:');
A_inv= inv(A_GF)
disp('The inverse of matrix A in the primitive field is:');
A_invv=double(A_inv.x)

% A*A_inv should equate to an identity matrix..
disp('Verifying.................................................:');
Identity=(A_inv)*A_GF

% Computing the generator matrix
disp('The generator matrix is:');
G=[eye(num_rows) mod(A_invv*B,2)]

%Transpose of generator matrix
disp('The transpose of the generator matrix is:');
GT=transpose(G)

fprintf('The message consists of %d bits\n', num_rows);
message=input('Enter the message bits:');
codeword= mod(GT*message',2)

_________________________________________________________________

The H_matrix I used initially is

H_matrix= [0 1 1 0 0 0;1 1 0 1 0 0;1 0 0 0 1 0;0 1 0 0 0 1]

I need to work with very larger matrices.. When I input a (50,34) H_matrix for example, I get this error message:

??? Index exceeds matrix dimensions

And it's the same for any other huge matrices...

[Jan]

Please use code formatting - follow the "Markup help" link to learn how to apply the different formats to improve the readability.

It is very helpful, if you post the complete error message, especially to know which line causes the error...

Answer 1

[Jan]

A standard method to find the cause of bugs is:

dbstop if error

Then Matlab stops when an error occurs and you can inspect the values of the used variables. Using the debugger is even more efficient than asking this powerful forum.

[Synchronie]

Thanks :)

Answer 2

[Synchronie]

Got a question.. Where should I input dbstop if error throughout my program????