Note on decoding binary Goppa codes

The author gives a simple expression for the polynomial y(x) which solves the polynomial equation y(x)²≡t(x) mod G(x), where t(x), y(x) and G(x) are polynomials over the field GF(2^m). The solution of such an equation is a step in the so called Patterson algorithm for decoding binary Goppa codes. The result may also be useful for other applications