// Follows Pedrotti Eq. 19-36
// Eq. 19-44 exclusively for phase difference across quarter thickness
public Complex getReflectionCoefficient() {
Complex gamma0 = Complex.valueOf(gammas[0], 0);
Complex gammaS = Complex.valueOf(gammas[gammas.length - 1], 0);
Complex m11 = transfer.get(0, 0);
Complex m12 = transfer.get(0, 1);
Complex m21 = transfer.get(1, 0);
Complex m22 = transfer.get(1, 1);
// Pedrotti, Eq. 19-36
// Complex r = (g0m11+g0gSm12-m21-gSm22)/(g0m11+g0gSm12+m21+gSm22)
Complex n1 = gamma0.times(m11);
Complex n2 = gamma0.times(gammaS).times(m12);
Complex n3 = m21;
Complex n4 = gammaS.times(m22);
Complex numerator = n1.plus(n2).minus(n3).minus(n4);
Complex denominator = n1.plus(n2).plus(n3).plus(n4);
Complex r = numerator.divide(denominator);
return r;
}