shortened code :
Suppose C is an [n,k,d] code over GF(q) and i is any integer satisfying 1 ≤ i ≤ n. The shortened code C'' at the coordinate i is the code having length n-1 obtained by projecting the subcode
{ c=(c1,...,cn) in C | ci=0 }
onto the remaining coordinates.
spectrum:
If AC(x,y) = Σi=0n Aixn-iyi is the weight enumerator of C, where
Ai = |{ c in C | wt(c)=i}|
denotes the number of codewords of weight i, then the spectrum of C is the list of coefficients of AC :
spec(C)=[A0, ... , An].