# berlekamp massey

Hello,

I am trying to use B/M algo included in Sage. Now,

berlekamp_massey([GF(2)(0),0,1,0,1,0,0,1,0,1,1,1,0,0,1,1,0,0,0,0,1,0,1,1,0,1,0,1,0,0,0,1,1,1,1,0])

evals to f(x)=x^5 + x^3 + x^2 + x + 1 which is the minimal poly. Also, I know that when I take the reciprocal (x^5*f(1/x)), I find g(x)=x^5+x^4+x^3+x^2+1 which is the connection poly. of this LFSR.

My question is how can I regenerate this sequence using this connection poly.? Providing initial states 0,0,1,0,1 yields to another sequence:

(0 0 1 0 1 1 0 1 0 1 0 0 0 1 1 1 0 1 1 1 1 1 0 0 1 0 0 1 1 0 0)

I think, there might be a bug in B/M implementation because other implementations give

x^19 + x^18 + x^17 + x^14 + x^13 + x^10 + x^9 + x^8 + x^6 + x^3 + x^2 + 1

when fed with the same sequence.

Thanks, evrim.