Automatic gridding

The simulation class comes new with an automatic gridding functionality, which should make it much easier to compute CSEM data. With that the entire optimization routine was improved too. See the API docs for more info of the relevant implementation.

• simulation:

  • Simulation: New gridding options 'single', 'frequency', 'source', and 'both'; new default is 'single'.
  • compute() takes a new argument, min_offset. If observed=True, it will add Gaussian random noise according to the standard deviation of the data; it will set receivers responses below the minimum offset to NaN.
  • There is no longer a reference model.
  • misfit and gradient can now handle observations with NaN's.

• survey: A Survey has new attributes standard_error, noise_floor, and relative_error.

• optimize: Completely changed misfit and data-weighting to more sensible functions.

• cli:

  • As a consequence of the changes the data_weight_opts got removed.
  • New sections [data] to select the wanted data and [gridding_opts] for options of the automatic gridding.
  • Section [simulation] has a new parameter min_offset (for creating observed data).
  • Output has a new parameter n_observations if misfit or gradient were called, which is the number of observations that were used to compute the misfit.

• meshes:

  • New functions construct_mesh, get_origin_widths, good_mg_cell_nr and other, smaller helper routines.
  • Deprecated the old meshing routines get_hx_h0, get_cell_numbers, get_stretched_h, get_domain, get_hx; they will be removed in the future.
  • Default of good_mg_cell_nr changed, and the documentation (and verbosity) with regards to «good» number of cells was improved.

• Bug fixes:

  • maps: Fixed the mapping of the gradients (Conductivity is the only mapping that was not affected by this bug).

• Removed deprecated features:

  • models.Model: Removed parameters res_{x;y;z}.
  • io.save: Removed deprecated parameter backend.
  • io.save: Removed default, file extension has to be provided.