These are examples of the flexibility of symfit Models. This is because essentially any valid sympy code can be provided as a model. This makes it very intuitive to define your mathematical models almost as you would on paper.
ex_fourier_series ex_piecewise ex_poly_surface_fit ex_ODEModel ex_ode_system.ipynb ex_CallableNumericalModel ex_CallableNumericalModel_ode.ipynb ex_tikhonov.ipynb
These are examples on how to use a different objective function from the standard least-squares objective, such as likelihood fitting.
ex_bivariate_likelihood.ipynb ex_multidataset_likelihood
These examples demonstrate the different minimizers available in symfit.
ex_mexican_hat.ipynb
The symfit.contrib.interactive_guess contrib module was designed to make the process of finding initial guesses easier, by presenting the user with an interactive matplotlib window in which they can play around with the initial values.
ex_interactive_guesses_ODE ex_interactive_guesses_vector_2D ex_interactive_guesses_nD