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June 15th, 2017, 06:15 AM
#1
LDPC:How to make LDPC parity check matrix H from non-systematic to systematic in C/C+
Hi,
I am working with KINTEX board for LDPC encoding and decoding.Through Vivado HLS, I need to transform a parity-check matrix H (that only consists of ones and zeros) from a non-standard to a standard form through C/C++ programming language. Here below you may find samples of non-standard parity check matrices in which Gauss-Jordan elimination (over GF(2)) can be applied.
Initially, i need C/C++ programming logic please help me if you do have any idea about LDPC. I would need a method that works out with matrices of any dimension.
this is, express it as
Hsys = [I| P]
This is my H matrix
H=[1 1 0 0 1 0;
1 0 0 1 0 1;
1 1 1 0 0 1 ];
Expected Systematic H matrix
Hsys=[1 0 0 1 0 1;
0 1 0 1 1 1;
0 0 1 0 1 1 ];
Code:
#include<stdio.h>
int main()
{
// encoding
int i,j;
int message;
int H_Matrix[3][6]={{1,1,0,0,1,0},{1,0,0,1,0,1},{1,1,1,0,0,1}};
int temp[3][6]={0};
for(j=0;j<6;j++)
{
temp[1][j]=(H_Matrix[1][j]^H_Matrix[0][j]);
H_Matrix[1][j] = temp[1][j];
temp[2][j]=(H_Matrix[2][j]^H_Matrix[0][j]);
H_Matrix[2][j] = temp[2][j];
temp[0][j]=(H_Matrix[0][j]^H_Matrix[1][j]);
H_Matrix[0][j] = temp[0][j];
}
for(i=0;i<3;i++)
{
for(j=0;j<6;j++)
{
printf("%d\t ",H_Matrix[i][j]);
}
printf("\n");
}
}
Logic
n=6 k=3 q=2
Start [0,0] = 1
Pivot [0,0] = 1
r_2 --> r_2 - r_1
r_3 --> r_3 - r_1
1 1 0 0 1 0
0 1 0 1 1 1
0 0 1 0 1 1
--
Start [1,1] = 1
Pivot [1,1] = 1
r_1 --> r_1 - r_2
1 0 0 1 0 1
0 1 0 1 1 1
0 0 1 0 1 1
--
Start [2,2] = 1
Pivot [2,2] = 1
1 0 0 1 0 1
0 1 0 1 1 1
0 0 1 0 1 1
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June 15th, 2017, 12:49 PM
#2
Re: LDPC:How to make LDPC parity check matrix H from non-systematic to systematic in
A friend of mine, has written Gauss eliminator which can be easily adopted for int values, here is the code:
Code:
void GaussEliminator::solve()
{
m_vecResult.clear();
std::vector<double> v(m_dataMatrix.size() + 1);
unsigned char curr_index = 0, add_index = 0;
//now triagonalize matrix
for (data_matrix::iterator i = m_dataMatrix.begin(), e = m_dataMatrix.end(), k; i != e; ++i, ++curr_index) {
//normalize next row
std::transform(i->begin(), i->end(), i->begin(), std::bind2nd(std::divides<double>(), *(i->begin() + curr_index)));
//remove that item from the next ones
for (k = i + 1; k != e; ++k) {
//base row
v.assign(i->begin(), i->end());
//multiply by the next modified row and then substract
std::transform(v.begin(), v.end(), v.begin(), std::bind2nd(std::multiplies<double>(), *(k->begin() + curr_index)));
std::transform(k->begin(), k->end(), v.begin(), k->begin(), std::minus<double>());
}
}
//now perform reverse process
curr_index = m_dataMatrix.size();
for (data_matrix::reverse_iterator i = m_dataMatrix.rbegin(), e = m_dataMatrix.rend(); i != e; ++i, ++add_index, --curr_index)
m_vecResult.push_front((i->back() - std::inner_product<std::vector<double>::iterator, std::deque<double>::iterator, double>(i->begin() + curr_index, i->end() - 1, m_vecResult.begin(), 0)));
}
Last edited by AvDav; June 15th, 2017 at 12:54 PM.
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June 15th, 2017, 11:22 PM
#3
Re: LDPC:How to make LDPC parity check matrix H from non-systematic to systematic in
Hi,
Thanks for your response. Really i can`t understand concept of your code. I am beginner in programming code (C/C++) so i request you to start from the main function.
This is my H matrix
H=[1 1 0 0 1 0;
1 0 0 1 0 1;
1 1 1 0 0 1 ];
Expected Systematic H matrix: Hsys = [Identity matrix | P] //Requirement:Initially, i need C/C++ programming logic please help me if you do have any idea about LDPC. I would need a method that works out with matrices of any dimension.
Hsys=[1 0 0 1 0 1;
0 1 0 1 1 1;
0 0 1 0 1 1 ];
Originally Posted by AvDav
A friend of mine, has written Gauss eliminator which can be easily adopted for int values, here is the code:
Code:
void GaussEliminator::solve()
{
m_vecResult.clear();
std::vector<double> v(m_dataMatrix.size() + 1);
unsigned char curr_index = 0, add_index = 0;
//now triagonalize matrix
for (data_matrix::iterator i = m_dataMatrix.begin(), e = m_dataMatrix.end(), k; i != e; ++i, ++curr_index) {
//normalize next row
std::transform(i->begin(), i->end(), i->begin(), std::bind2nd(std::divides<double>(), *(i->begin() + curr_index)));
//remove that item from the next ones
for (k = i + 1; k != e; ++k) {
//base row
v.assign(i->begin(), i->end());
//multiply by the next modified row and then substract
std::transform(v.begin(), v.end(), v.begin(), std::bind2nd(std::multiplies<double>(), *(k->begin() + curr_index)));
std::transform(k->begin(), k->end(), v.begin(), k->begin(), std::minus<double>());
}
}
//now perform reverse process
curr_index = m_dataMatrix.size();
for (data_matrix::reverse_iterator i = m_dataMatrix.rbegin(), e = m_dataMatrix.rend(); i != e; ++i, ++add_index, --curr_index)
m_vecResult.push_front((i->back() - std::inner_product<std::vector<double>::iterator, std::deque<double>::iterator, double>(i->begin() + curr_index, i->end() - 1, m_vecResult.begin(), 0)));
}
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June 16th, 2017, 12:01 AM
#4
Re: LDPC:How to make LDPC parity check matrix H from non-systematic to systematic in
1) Well, I have no idea on what LDPC is.
2) I just thought the code can be useful for this purpose and really it can work out with matrix of arbitrary NxM dimensions.
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