// 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;
  }