Using the perturbation method we have got the fourth orderofapproximation of the velocity potential to the problem.
运用摄动方法，给出了速度势的四阶近似，然后得到了圆柱表面的无量纲的压力系数和阻力系数。
2
The best orderofapproximation by (N, P) means of T-F series is discussed, and asufficient condition to reach this order is found.
讨论了算子（N，P）的最佳逼近阶以及达到此逼近阶的一个充分条件。
3
The approximationof differentiable functions by a kind of interpolatory rational functions is discussed, and the corresponding orderofapproximation is obtained.