galois.FLFSR.feedback_poly

property galois.FLFSR.feedback_poly : Poly

The feedback polynomial \(f(x) = -c_{0}x^{n} - c_{1}x^{n-1} - \dots - c_{n-2}x^{2} - c_{n-1}x + 1\) that defines the feedback arithmetic.

Notes¶

The feedback polynomial is the reciprocal of the characteristic polynomial \(f(x) = x^n c(x^{-1})\).

Examples¶

In [1]: c = galois.primitive_poly(7, 4); c
Out[1]: Poly(x^4 + x^2 + 3x + 5, GF(7))

In [2]: lfsr = galois.FLFSR(c.reverse()); lfsr
Out[2]: <Fibonacci LFSR: f(x) = 5x^4 + 3x^3 + x^2 + 1 over GF(7)>

In [3]: lfsr.feedback_poly
Out[3]: Poly(5x^4 + 3x^3 + x^2 + 1, GF(7))

In [4]: lfsr.feedback_poly == lfsr.characteristic_poly.reverse()
Out[4]: True