docs: def restore(self, filename):
          """Restore object from mat-file. TODO: determine format specification
          """
          matfile = loadmat(filename)
  
          if matfile['dim'] == 1:
              matfile['solution'] = matfile['solution'][0, :]
  
          self.elapsed_time = matfile['elapsed_time'][0, 0]
          self.solution = matfile['solution']
  
          return self