65.90 PermutedCode

PermutedCode( C, L )

PermutedCode returns C after column permutations. L is the permutation to be executed on the columns of C. If C is cyclic, the result in general is no longer cyclic. If a permutation results in the same code as C, this permutation belongs to the automorphism group of C (see AutomorphismGroup). In any case, the returned code is equivalent to C (see IsEquivalent).

    gap> C1 := PuncturedCode( ReedMullerCode( 1, 4 ) );
    a linear [15,5,7]5 punctured code
    gap> C2 := BCHCode( 15, 7, GF(2) );
    a cyclic [15,5,7]5 BCH code, delta=7, b=1 over GF(2)
    gap> C2 = C1;
    false
    gap> p := CodeIsomorphism( C1, C2 );
    ( 2,13, 7,10, 8, 3, 5, 4,14)(12,15)
    gap> C3 := PermutedCode( C1, p );
    a linear [15,5,7]5 permuted code
    gap> C2 = C3;
    true 

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