alist2sparse.m

LDPC编码的GFQ程序源代码

function [H] = alist2sparse(fname)
% reads binary parity check matrix in "alist" format from file FNAME and
% converts it to sparse matrix used in MATLAB routines.
% This is an interface to matrices at http://wol.ra.phy.cam.ac.uk/mackay/codes/
%
% Example
%        [H] = alist2sparse('A');   % A is the ascii file in alist format


%   Copyright (c) 1999 by Igor Kozintsev [e-mail]
%   $Revision: 1.1 $  $Date: 2000/03/23 $ Bug fixed by Hatim Behairy

fid = fopen(fname);
n = fscanf(fid,'%d',1);
m = fscanf(fid,'%d',1);
maxinrow = fscanf(fid,'%d',1); 
junk = fscanf(fid,'%d',1); % no need
num = fscanf(fid,'%d',[1 n]); % number of elements in rows

num2(1:n)=maxinrow;    
junk = fscanf(fid,'%d',[1 m]); % no need

position = zeros(n,maxinrow);
for i=1:n
   for j=1:num2(i)    
      position(i,j) = fscanf(fid,'%d',1);
   end
end

ii = zeros(1,sum(num));
jj = ii;
k = 1;
for i=1:n
      for j=1:num(i)
      jj(k) = i;
      ii(k) = position(i,j);
      ss = 1;
      k = k+1 ; 
   end
end
H = sparse(ii,jj,ss,m,n);
fclose(fid);