How to create generator matrix from polynomial for linear block code?

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Anyone can help me step by step to create generator matrix from polynomial? I have checked in many blogs but didn't understand.( Even i don't know what are mathematics required).







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    I would look at books rather than blogs.
    – Lord Shark the Unknown
    Aug 24 at 5:32














up vote
1
down vote

favorite












Anyone can help me step by step to create generator matrix from polynomial? I have checked in many blogs but didn't understand.( Even i don't know what are mathematics required).







share|cite|improve this question
















  • 3




    I would look at books rather than blogs.
    – Lord Shark the Unknown
    Aug 24 at 5:32












up vote
1
down vote

favorite









up vote
1
down vote

favorite











Anyone can help me step by step to create generator matrix from polynomial? I have checked in many blogs but didn't understand.( Even i don't know what are mathematics required).







share|cite|improve this question












Anyone can help me step by step to create generator matrix from polynomial? I have checked in many blogs but didn't understand.( Even i don't know what are mathematics required).









share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Aug 24 at 5:15









Chandramohan V

61




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  • 3




    I would look at books rather than blogs.
    – Lord Shark the Unknown
    Aug 24 at 5:32












  • 3




    I would look at books rather than blogs.
    – Lord Shark the Unknown
    Aug 24 at 5:32







3




3




I would look at books rather than blogs.
– Lord Shark the Unknown
Aug 24 at 5:32




I would look at books rather than blogs.
– Lord Shark the Unknown
Aug 24 at 5:32










1 Answer
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If you have a finite field $k$, then a polynomial $f(X)$ is a generating polynomial for a linear code of length $n$ over $k$ iff it is a factor of $X^n-1$ over $k$.
Then we can write $f(X)=a_0+a_1X+a_2X^2+cdots+a_dX^d$ where $d$ is the degree
of $f(X)$ and $a_dne0$. This generates a code with dimension $n-d$
and generator matrix
$$G=pmatrixa_0&a_1&a_2&cdots&a_d&0&0&cdots&0\
0&a_0&a_1&cdots&a_d-1&a_d&0&cdots&0\
0&0&a_0&cdots&a_d-2&a_d-1&a_d&cdots&0\
vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots\
0&0&cdots&0&a_0&a_1&a_2&cdots&a_d.$$
There are $n-d$ rows, and each row after the first is obtained by shifting
the previous row cyclically right by one position.






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  • That's the way it works in theory. In practice telcomm folks often use shortened cyclic codes. That amounts to leaving out a fixed number of columns from the right end as well as the same number of rows from the bottom. You see, in practice somebody other than the coding theorist decides the rank and the length of the code.
    – Jyrki Lahtonen
    Aug 24 at 6:07










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1 Answer
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up vote
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If you have a finite field $k$, then a polynomial $f(X)$ is a generating polynomial for a linear code of length $n$ over $k$ iff it is a factor of $X^n-1$ over $k$.
Then we can write $f(X)=a_0+a_1X+a_2X^2+cdots+a_dX^d$ where $d$ is the degree
of $f(X)$ and $a_dne0$. This generates a code with dimension $n-d$
and generator matrix
$$G=pmatrixa_0&a_1&a_2&cdots&a_d&0&0&cdots&0\
0&a_0&a_1&cdots&a_d-1&a_d&0&cdots&0\
0&0&a_0&cdots&a_d-2&a_d-1&a_d&cdots&0\
vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots\
0&0&cdots&0&a_0&a_1&a_2&cdots&a_d.$$
There are $n-d$ rows, and each row after the first is obtained by shifting
the previous row cyclically right by one position.






share|cite|improve this answer




















  • That's the way it works in theory. In practice telcomm folks often use shortened cyclic codes. That amounts to leaving out a fixed number of columns from the right end as well as the same number of rows from the bottom. You see, in practice somebody other than the coding theorist decides the rank and the length of the code.
    – Jyrki Lahtonen
    Aug 24 at 6:07














up vote
0
down vote













If you have a finite field $k$, then a polynomial $f(X)$ is a generating polynomial for a linear code of length $n$ over $k$ iff it is a factor of $X^n-1$ over $k$.
Then we can write $f(X)=a_0+a_1X+a_2X^2+cdots+a_dX^d$ where $d$ is the degree
of $f(X)$ and $a_dne0$. This generates a code with dimension $n-d$
and generator matrix
$$G=pmatrixa_0&a_1&a_2&cdots&a_d&0&0&cdots&0\
0&a_0&a_1&cdots&a_d-1&a_d&0&cdots&0\
0&0&a_0&cdots&a_d-2&a_d-1&a_d&cdots&0\
vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots\
0&0&cdots&0&a_0&a_1&a_2&cdots&a_d.$$
There are $n-d$ rows, and each row after the first is obtained by shifting
the previous row cyclically right by one position.






share|cite|improve this answer




















  • That's the way it works in theory. In practice telcomm folks often use shortened cyclic codes. That amounts to leaving out a fixed number of columns from the right end as well as the same number of rows from the bottom. You see, in practice somebody other than the coding theorist decides the rank and the length of the code.
    – Jyrki Lahtonen
    Aug 24 at 6:07












up vote
0
down vote










up vote
0
down vote









If you have a finite field $k$, then a polynomial $f(X)$ is a generating polynomial for a linear code of length $n$ over $k$ iff it is a factor of $X^n-1$ over $k$.
Then we can write $f(X)=a_0+a_1X+a_2X^2+cdots+a_dX^d$ where $d$ is the degree
of $f(X)$ and $a_dne0$. This generates a code with dimension $n-d$
and generator matrix
$$G=pmatrixa_0&a_1&a_2&cdots&a_d&0&0&cdots&0\
0&a_0&a_1&cdots&a_d-1&a_d&0&cdots&0\
0&0&a_0&cdots&a_d-2&a_d-1&a_d&cdots&0\
vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots\
0&0&cdots&0&a_0&a_1&a_2&cdots&a_d.$$
There are $n-d$ rows, and each row after the first is obtained by shifting
the previous row cyclically right by one position.






share|cite|improve this answer












If you have a finite field $k$, then a polynomial $f(X)$ is a generating polynomial for a linear code of length $n$ over $k$ iff it is a factor of $X^n-1$ over $k$.
Then we can write $f(X)=a_0+a_1X+a_2X^2+cdots+a_dX^d$ where $d$ is the degree
of $f(X)$ and $a_dne0$. This generates a code with dimension $n-d$
and generator matrix
$$G=pmatrixa_0&a_1&a_2&cdots&a_d&0&0&cdots&0\
0&a_0&a_1&cdots&a_d-1&a_d&0&cdots&0\
0&0&a_0&cdots&a_d-2&a_d-1&a_d&cdots&0\
vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots&vdots\
0&0&cdots&0&a_0&a_1&a_2&cdots&a_d.$$
There are $n-d$ rows, and each row after the first is obtained by shifting
the previous row cyclically right by one position.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Aug 24 at 5:31









Lord Shark the Unknown

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  • That's the way it works in theory. In practice telcomm folks often use shortened cyclic codes. That amounts to leaving out a fixed number of columns from the right end as well as the same number of rows from the bottom. You see, in practice somebody other than the coding theorist decides the rank and the length of the code.
    – Jyrki Lahtonen
    Aug 24 at 6:07
















  • That's the way it works in theory. In practice telcomm folks often use shortened cyclic codes. That amounts to leaving out a fixed number of columns from the right end as well as the same number of rows from the bottom. You see, in practice somebody other than the coding theorist decides the rank and the length of the code.
    – Jyrki Lahtonen
    Aug 24 at 6:07















That's the way it works in theory. In practice telcomm folks often use shortened cyclic codes. That amounts to leaving out a fixed number of columns from the right end as well as the same number of rows from the bottom. You see, in practice somebody other than the coding theorist decides the rank and the length of the code.
– Jyrki Lahtonen
Aug 24 at 6:07




That's the way it works in theory. In practice telcomm folks often use shortened cyclic codes. That amounts to leaving out a fixed number of columns from the right end as well as the same number of rows from the bottom. You see, in practice somebody other than the coding theorist decides the rank and the length of the code.
– Jyrki Lahtonen
Aug 24 at 6:07

















 

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