def _compute_simulation_parameters(dictionary):
    """
    Utility that computes the relevant physical parameters
    starting from the input file.
    """
    dictionary['dx'] = 1.0 / dictionary['k0']
    if dictionary['n_dimensions'] == 1:
        return
    if 'yx_rat' in dictionary.keys():
        dictionary['dy'] = dictionary['yx_rat'] * dictionary['dx']
    else:
        dictionary['dy'] = dictionary['dx']
    if dictionary['n_dimensions'] == 2:
        return
    if 'zx_rat' in dictionary.keys():
        dictionary['dz'] = dictionary['zx_rat'] * dictionary['dx']
    else:
        dictionary['dz'] = dictionary['dy']
    if dictionary['str_flag'] > 0:
        dictionary['stretched'] = True
