Update dynamical_system.py

dynamical_system.py

@@ -7,3 +7,8 @@ def invasion_fitness2(z, zm, pars):
     alpha, beta = pars
     n_res = (z - z**beta) / alpha
     return zm - zm**beta - alpha * n_res
+
+
+def pop_dynamics2(t, n, pars):
+    alpha, beta, z = pars
+    return n * (z - z**beta - alpha * n)