property sdr.GLFSR.feedback_poly : Poly

The feedback polynomial \(f(x)\) that defines the feedback arithmetic.

Notes

The feedback polynomial \(f(x) = -c_{0} \cdot x^{n} - c_{1} \cdot x^{n-1} - \dots - c_{n-2} \cdot x^{2} - c_{n-1} \cdot x + 1\) is the reciprocal of the characteristic polynomial \(f(x) = x^n \cdot c(x^{-1})\).

Examples

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

In [2]: lfsr = sdr.GLFSR(c); lfsr
Out[2]: <Galois LFSR: c(x) = x^4 + x^2 + 3x + 5 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