'obsolete and subject to removal (TODO),
return modified f-values such that for each mirror one becomes worst.
This function is useless when selective mirroring is applied with no
more than (lambda-mu)/2 solutions.
Mirrors are leading and trailing values in ``f_values``.'

def mirror_penalized(self, f_values, idx):

    assert (len(f_values) >= (2 * len(idx)))
    m = np.max(np.abs(f_values))
    for i in len(idx):
        if (f_values[idx[i]] > f_values[((-1) - i)]):
            f_values[idx[i]] += m
        else:
            f_values[((-1) - i)] += m
    return f_values
