White noise

• CLI:

  • New parameters save and load to save and load an entire simulation.
    In the parameter file, they are under [files]; on the command line,
    they are available as --save and --load; they are followed by the
    filename including its path and suffix. (In turn, the parameter
    store_simulation was removed.)

• simulations.Simulation:

  • Warns if the gradient is called, but receiver_interpolation is not
    'linear'.
  • Slightly changed the added noise in compute(observed=True): It uses new
    the survey.add_noise attribute. There is new a flag to set if noise
    should be added or not (add_noise), and if the amplitudes should be
    chopped or not (min_amplitude). Also note that the added noise is new
    white noise with constant amplitude and random phase.

• surveys:

  • New function random_noise, which can be used to create random noise in
    different ways. The default noise is white noise, hence constant amplitude
    with random phase. (This is different to before, where random Gaussian
    noise was added separately to the real and imaginary part.) For the random
    noise it requires new at least NumPy 1.17.0.

  • New attribute Survey.add_noise, which uses under the hood above
    function.

  • A Survey can new be instantiated without receivers by setting
    receivers to None. This is useful if one is only interested in
    forward modelling the entire fields. In this case, the related data object
    and the noise floor and relative error have no meaning. Also, in
    conjunction with a Simulation, the misfit and the gradient will be zero.

• Various:

  • All emg3d-warnings (not solver warnings) are now set to 'always', and
    corresponding print statements were removed.
  • Simplified (unified) _edge_curl_factor (private fct).