In general, experience has shown that third-to fifth-degree polynomials produce sufficiently low residuals and monotonically increasing derivatives .
实践证明,三至五次多项式就能产生足够小的残差和单调递增的导数。
2
The second critical decision came in 1979 when it was required that every teacher gain a fifth-year Master's degree in theory and practice, paid for by the state.