exotic_ld.ld_laws.nonlinear_4param_ld_law

exotic_ld.ld_laws.nonlinear_4param_ld_law(mu, u1, u2, u3, u4)

Non-linear 4-parameter limb-darkening law.

\[\frac{I(\mu)}{I(\mu = 1)} = 1 - u_1 (1 - \mu^{0.5}) - u_2 (1 - \mu) - u_2 (1 - \mu^{1.5}) - u_3 (1 - \mu^2),\]

where \(\mu = \sqrt{1 - r^2}\), and \(u_1\), \(u_2\), \(u_3\), \(u_4\) are the limb-darkening coefficients.