code: def write_unitary_matrix_to_hdf5(temperature,
                                   mesh,
                                   unitary_matrix=None,
                                   sigma=None,
                                   sigma_cutoff=None,
                                   solver=None,
                                   filename=None,
                                   verbose=False):
      
  
      suffix = _get_filename_suffix(mesh,
                                    sigma=sigma,
                                    sigma_cutoff=sigma_cutoff,
                                    filename=filename)
      hdf5_filename = "unitary" + suffix + ".hdf5"
      with h5py.File(hdf5_filename, 'w') as w:
          w.create_dataset('temperature', data=temperature)
          if unitary_matrix is not None:
              w.create_dataset('unitary_matrix', data=unitary_matrix)
          if solver is not None:
              w.create_dataset('solver', data=solver)
  
          if verbose:
              if len(temperature) > 1:
                  text = "Unitary matrices "
              else:
                  text = "Unitary matrix "
              if sigma is not None:
                  text += "at sigma %s " % _del_zeros(sigma)
                  if sigma_cutoff is not None:
                      text += "(%4.2f SD) " % sigma_cutoff
              if len(temperature) > 1:
                  text += "were written into "
              else:
                  text += "was written into "
              if sigma is not None:
                  text += "\n"
              text += "\"%s\"." % hdf5_filename
              print(text)
docs: Write eigenvectors of collision matrices at temperatures.
  
      Depending on the choice of the solver, eigenvectors are sotred in
      either column-wise or row-wise.