def _reconstruct(x, y, r1, r2, ll, gamma, rho, sigma):
    """Reconstruct solution velocity vectors."""
    V_r1 = gamma * ((ll * y - x) - rho * (ll * y + x)) / r1
    V_r2 = -gamma * ((ll * y - x) + rho * (ll * y + x)) / r2
    V_t1 = gamma * sigma * (y + ll * x) / r1
    V_t2 = gamma * sigma * (y + ll * x) / r2
    return [V_r1, V_r2, V_t1, V_t2]