FRC_AB

function [a, b] = frc_ab(rho,omega,gamma,lambda)

This function evaluates the autonomous reduced dynamics on the parametrisation coordinates, for a 2D SSM

[a, b] = FRC_AB(rho,omega,gamma,lambda)

rho: parametrisation coordinate polar amplitude

omega: forcing frequency

gamma: reduced dynamics coefficients

lambda: master mode eigenvalue

a: contribution to the amplitude ODE of the reduced dynamics

b: contribution to the angle ODE of the reduced dynamics

See also: COMPUTE_REDUCED_DYNAMICS_2D_POLAR

a = rho * real(lambda);
b = rho .* (imag(lambda) - omega);

for j = 1:length(gamma)
    a = a + real(gamma(j))* rho.^(2*j+1);
    b = b + imag(gamma(j)) * (rho.^(2*j+1));
end

end