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].