D.9.1.11 dual_code
..................
Procedure from library brnoeth.lib (see brnoeth_lib).

Usage:
dual_code(G); G a matrix of numbers

Return:
a generator matrix of the dual code generated by G

Note:
The input should be a matrix G of numbers. 

The output is also a parity check matrix for the code defined by G

Example:
LIB "brnoeth.lib";
ring s=2,T,lp;
// here is the Hamming code of length 7 and dimension 3
matrix G[3][7]=1,0,1,0,1,0,1,0,1,1,0,0,1,1,0,0,0,1,1,1,1;
print(G);
==> 1,0,1,0,1,0,1,
==> 0,1,1,0,0,1,1,
==> 0,0,0,1,1,1,1 
matrix H=dual_code(G);
print(H);
==> 1,1,1,0,0,0,0,
==> 1,0,0,1,1,0,0,
==> 0,1,0,1,0,1,0,
==> 1,1,0,1,0,0,1 

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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; User manual for <a href="http://www.singular.uni-kl.de/"><i>Singular</i></a> version 2-0-4, October 2002,
generated by <a href="http://www.gnu.org/software/texinfo/"><i>texi2html</i></a>.
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