approximate function的用法和樣例：
例句
- In the finite element method, one of the restrictions on the approximating functions is relaxed.
在有限單元方法中，放開了定近似函數的限制。 - It is difficult to settle essential boundary conditions in meshless method because the meshless approximation functions are not built by interpolation schemes.
摘要無網格法中的近似函數大都不是插值函數，在處理本質邊界條件時較為困難。
