Bose_classII_w3.m

%Copyright(c) 2011, USAtyuk Vasiliy 
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%Class-|| (weight 3)
% Application generate QC-LDPC parity-check matrix based on BOSE BIBD
% (which define Quasi-cyclic BOSE BIBD-LDPC (and can be generalized) 
% from GF(q) extender shall have size of field q-1
%  size of mother matrix depend of choise of rows which produce non-full
% matrix from W
clear all;

%
%if field great then 500, don't forget to change recursion limit in matlab
%to value above field charachteristic, example set(0,'RecursionLimit',700)
%p= 613; % 
%GF(6t+1)
%p=613;
%t=102; 
p=1201;
t=200; 
%t=30; %(t=21 for 421) %  c<=t, prime characteristic of field 
%a=7; % primitive  e     lement of 
a=11; %primitive element
k=0;
columnweight=3;
%rowweight=30; % must be less or equal t
rowweight=10;
exp(columnweight,rowweight)=zeros();
for i = 1:rowweight
    for j = 1:columnweight 
          exp(j,i)=mod(p+1-fldpow(2*(i-1)+2*t*(j-1),a,p),p);
    end
end



C(p,p)=sparse(zeros());
circ(p,p)=sparse(zeros());
for i = 1:rowweight
    
    for j = 1:columnweight
C=C+circshift(eye(p), exp(j,i));
    end
    
    if i==1
    circ=C;
    end
    if i>1
    circ=cat(2,circ,C);
    end
    C=zeros();
end
%To estimate lower bound of code distance 
%C(p,p)=sparse(zeros());
%H_=[zeros(421,421),H; H',zeros(8841,8841)];
%[V,D] = eig(H_);