simpeg.flow.richards.empirical.Haverkamp_theta.derivM

Haverkamp_theta.derivM(u)

derivative with respect to m

import sympy as sy

alpha, u, beta, theta_r, theta_s = sy.symbols(
    'alpha u beta theta_r theta_s', real=True
)

f_n = (
    alpha *
    (theta_s - theta_r) /
    (alpha + abs(u)**beta) +
    theta_r
)