Hi, I am trying to make a parity check matrix from non-systematic to systematic. Hence I am attaching my code below. Somewhat it is correct, but there are some problems. It would be really great if someone could help me in this. Thanks

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sb 2016-6-9

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评论： SP22 2017-11-20

check.m

Information theory and coding. I am working on LDPC coding and decoding. Please check the code below

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Walter Roberson 2016-6-9

Do we get some hints about what the problems are ?

sb 2016-6-10

编辑：Walter Roberson 2017-5-25

在 MATLAB Online 中打开

For e.g.

This is my H matrix

H =
   0     1     1     0
   0     1     0     1
   0     0     1     0
   0     1     1     1

I want to have an identity matrix inside the matrix. the dimension on H matrix here is (mxn) which is (4x5).

I should have matrix as this in the result:

Hsys =
   1     0     0     0
   0     1     0     0
   0     0     1     0
   0     0     0     1

I should have an identity matrix of dimension 'm'

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Answer 1

freebil 2016-6-10

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在 MATLAB Online 中打开

You have to do gauss jordan elimination to convert a parity check matrix to upper triangular form. For example,

H=[1 1 0 1 1 0 0 1 0 0;
1 1 0 1 1 1 0 0 0;
0 0 1 0 0 0 1 1 1;
1 0 0 0 1 1 0 1 0;
0 1 0 0 1 0 1 0 1];

There is rref() in matlab and you have to do it in GF(2). So,

HH = mod(rref(H),2)

gives

HH = 1     0     0     0     0     0     1     1     1     0
   1     0     0     0     1     0     1     0     0
   0     1     0     0     1     0     1     0     1
   0     0     1     0     0     0     1     1     1
   0     0     0     1     1     1     0     0     1