Note that this reference documentation is identical to the help that is displayed in MATLAB when you type “help ft_denoise_synthetic”.

  FT_DENOISE_SYNTHETIC computes CTF higher-order synthetic gradients for
  preprocessed data and for the corresponding gradiometer definition.
  Use as
    [data] = ft_denoise_synthetic(cfg, data);
  where data should come from FT_PREPROCESSING and the configuration should contain
    cfg.gradient = 'none', 'G1BR', 'G2BR' or 'G3BR' specifies the gradiometer
                   type to which the data should be changed
    cfg.trials   = 'all' or a selection given as a 1xN vector (default = 'all')
  To facilitate data-handling and distributed computing you can use
    cfg.inputfile   =  ...
    cfg.outputfile  =  ...
  If you specify one of these (or both) the input data will be read from a *.mat
  file on disk and/or the output data will be written to a *.mat file. These mat
  files should contain only a single variable, corresponding with the
  input/output structure.