论文标题

快速评估真实和复杂的多项式

Fast Evaluation of Real and Complex Polynomials

论文作者

Anton, Ramona, Mihalache, Nicolae, Vigneron, François

论文摘要

我们提出了一种用于快速评估多项式的​​算法。它预先提前一个复杂的多项式$ p $度$ d $ in Time $ o(d \ log d)$,具有低乘法常数独立于精度。以$ p $位的固定精度计算的$ p $的随后评估平均算术复杂性$ o \ big(\ sqrt {d(p+\ log d)} \ big)$和内存$ O(dp)$。平均复杂度是根据\ at \ Mathbb {C} $的点计算的,由$ \ overline {\ Mathbb {c}} $加权。最坏的情况并不超过H {Ö} Rner方案的复杂性。特别是,我们的算法每次评估均为$ o(\ sqrt {d \ log d})$渐近地执行。对于许多类别的多项式,尤其是在$ \ mathbb {c} $的有界区域中随机系数的那些类别,或对于稀疏的多项式,我们的算法的性能比该上限要好得多,而无需任何修改或参数化。文章都包含对复杂性和完整误差分析的详细分析,并保证了一个算法,并保证了Algorsh的效果,并保证了AlgoRith的效果。 快点。我们的算法在用标准C编写的同伴库中实施,并作为开源项目发布[MV22]。我们关于复杂性和准确性的主张在实践中通过一组全面的基准确认。

We propose an algorithm for quickly evaluating polynomials. It pre-conditions a complex polynomial $P$ of degree $d$ in time $O(d\log d)$, with a low multiplicative constant independent of the precision. Subsequent evaluations of $P$ computed with a fixed precision of $p$ bits are performed in average arithmetic complexity $O\big(\sqrt{d(p+\log d)}\big)$ and memory $O(dp)$. The average complexity is computed with respect to points $z \in \mathbb{C}$, weighted by the spherical area of $\overline{\mathbb{C}}$. The worst case does not exceed the complexity of H{ö}rner's scheme. In particular, our algorithm performs asymptotically as $O(\sqrt{d\log d})$ per evaluation. For many classes of polynomials, in particular those with random coefficients in a bounded region of $\mathbb{C}$, or for sparse polynomials, our algorithm performs much better than this upper bound, without any modification or parameterization.The article contains a detailed analysis of the complexity and a full error analysis, which guarantees that the algorithm performs as well as H\''orner's scheme, only faster. Our algorithm is implemented in a companion library, written in standard C and released as an open-source project [MV22].Our claims regarding complexity and accuracy are confirmed in practice by a set of comprehensive benchmarks.

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