To modify the final matrix H1 to achieve different code rates, you can add extra rows and columns with the required number of ones. Here is a possible way to do it:
- Determine the desired code rate.
- Calculate the number of extra rows and columns needed to achieve that code rate.
- Add the extra rows and columns to the matrix H1.
% Desired code rate
code_rate = 3/4;
% Determine the number of extra rows and columns needed
num_extra_rows = round((1/code_rate - 1) * m);
num_extra_cols = num_extra_rows;
% Create the extra rows and columns
extra_rows = repmat(eye(m), num_extra_rows, 1);
extra_cols = repmat(eye(m), 1, num_extra_cols);
% Add the extra rows and columns to H1
H1_modified = [H1 extra_cols];
H1_modified = [H1_modified; extra_rows];
% Number of ones in each row/column
ones_c_modified = sum(H1_modified, 1);
ones_r_modified = sum(H1_modified, 2);
% Check if the modified matrix is regular
dvi_modified = sum(H1_modified, 1);
dci_modified = sum(H1_modified, 2)';
[adv_modified, bdv_modified] = hist(dvi_modified, unique(dvi_modified));
[adc_modified, bdc_modified] = hist(dci_modified, unique(dci_modified));
dv_modified = sum((adv_modified ./ sum(adv_modified)) .* bdv_modified);
dc_modified = sum((adc_modified ./ sum(adc_modified)) .* bdc_modified);
if max(dv_modified) == min(dv_modified) && max(dc_modified) == min(dc_modified)
disp('Modified matrix is regular')
else
disp('Modified matrix is irregular')
end
spy(H1_modified);
