Theorem 1.7.6 Let
C
be a code over
F_(q)
. The following hold: (i) If
M
is a monomial matrix with entries only from
{0,-1,1}
, then
C
is self-dinal if and only if CM is self-dual.
C~=C_(1)
c=c^(2)<=>c_(1)=c_(1)^(-)
(ii) If
q=3
and
C
is equivalenti to
C_(1)
, then
C
is self-dual if and only if
C_(1)
is self-dual. (iii) If
q=4
and
C
is equivalent to
C_(1)
/then
C
is Hermitian self-dual if and only if
C_(1)
is Hermitian self-dinal.
c=c^(2 1)<=>c_(1)=c^(2 1)