共查询到20条相似文献,搜索用时 125 毫秒
1.
运用二分法,结合实系数多项式零点的界定理及Sturm定理,给出了一个求解一元实系数多项式方程全部实根的实用数值方法. 相似文献
2.
Laplace积分在复变函数、数学分析、Fourier分析中有重要的应用,其求解已有复变函数方法和实方法.在实方法中要用到∫∞0sinxxdx=π2,本文给出另外一种实方法,不需要利用这个积分. 相似文献
3.
二分法可用于求方程的近似解,在处理一类函数零点存在性问题时,利用二分法也可使问题快速获解,达到事半功倍的效果.例1已知函数f(x)=ax~3+bx~2+(b-a)x(a,b是均不为零的常数),其导函数为f′(x),求证:函数y=f′(x)在(-1,0)内至少存在一个零点. 相似文献
4.
5.
6.
7.
8.
新课改使学生接触到很多实际问题,而问题的解决往往求助于解方程,对于无公式且不能因式分解的方程,比如超越方程,学生感到束手无策.方程求解也即求函数零点,教材介绍了二分法.为了扩大学生的视野,帮助学生更好地解决实际问题,本文介绍几种零点近似值的探求方法.一、二分法例1求函数f(x)=lnx 2x-6在区间(2,3)内的零点(精确度为0.01).解:设函数f(x)在(2,3)内的零点为x0,用计算器计算得:f(2)<0,f(3)>0x0∈(2,3);f(2.5)<0,f(3)>0x0∈(2.5,3);f(2.5)<0,f(2.75)>0x0∈(2.5,2.75);f(2.5)<0,f(2.5625)>0x0∈(2.5,2.5625);f(2.53125)<0,f(2.5625)>0x0… 相似文献
9.
函数的零点主要涉及三个方面的问题:连续函数零点的存在性;连续函数零点个数的判定;求连续函数零点的近似解(二分法).在以上三个问题的考查中,常常涉及到参数取值范围的求解,主要从问题的逆向方面进行考察.这类问题是目前新课标下高考的重点、难点、热点,如何引导学生解决这类问题?笔者认为应从两方面入手. 相似文献
10.
11.
F. L. Chen & J. Kozak 《计算数学(英文版)》1996,14(3):237-248
1.IntroductionIn[6]and[4],theproblemoffindingtheintersectionofacubicB6zierpatchandaplanewasconsidered.[6]consideredarectangular,and[41atriangularpatch.SincetheBernsteinoperatorB.:f-Bn(f)preserveslinearfunctions,theproblemwassimplifiedtothecomputationofzerosofabivariateBernsteinpolynomialB.(f).BothpaPersproducedsimpleandefficientcomputationalalgorithms.Itisbaseduponthefollowingidea:determinethepointswhereinsidethesupportthetopologyofzerosofB.(f)changes.Thiswasdonebyrestrictingthebivariatepo… 相似文献
12.
Miodrag S. Petkovi 'c Carsten Carstensen Miroslav Trajkov ' i c 《Numerische Mathematik》1995,69(3):353-372
Summary.
Classical Weierstrass' formula
[29] has been often the subject of investigation of many
authors. In this paper we give some further
applications of this formula for finding the zeros of polynomials and
analytic functions. We are concerned with the problems of
localization of polynomial zeros and the construction of iterative methods for
the simultaneous approximation and inclusion of these zeros.
Conditions for the safe convergence of Weierstrass' method,
depending only on initial approximations, are given. In particular,
we study polynomials with interval coefficients. Using an interval
version of Weierstrass' method enclosures in the form of disks
for the complex-valued set containing all zeros of a
polynomial with varying coefficients are obtained. We also present
Weierstrass-like algorithm for approximating, simultaneously, all
zeros of a class of analytic functions in a given closed region.
To demonstrate the proposed algorithms, three numerical
examples are included.
Received September 13, 1993 相似文献
13.
Finding all zeros of polynomial systems is very interesting and it is also useul for many applied science problems.In this paper,based on Wu‘s method,we give an algorithm to find all isolated zeros of polynomial systems (or polynomial equations).By solving Lorenz equations,it is shown that our algo-rithm is efficient and powerful. 相似文献
14.
Summary.
It is well known that the zeros of a polynomial are equal to
the
eigenvalues of the associated companion matrix . In this paper
we take a
geometric view of the conditioning of these two problems and of the stability of
algorithms for polynomial zerofinding. The
is the set of zeros of all polynomials obtained by
coefficientwise perturbations of of size ;
this is a subset of the
complex plane considered earlier by Mosier, and is bounded by a
certain generalized lemniscate. The
is another subset of
defined as the set of eigenvalues of matrices
with ; it is bounded by a
level curve of the resolvent
of $A$. We find that if $A$ is first balanced in the usual EISPACK sense, then
and
are usually quite close to one another. It follows that the Matlab
ROOTS algorithm of balancing the companion matrix, then computing its eigenvalues, is a stable
algorithm for polynomial zerofinding. Experimental comparisons with the
Jenkins-Traub (IMSL) and
Madsen-Reid (Harwell) Fortran codes confirm that these three algorithms have roughly
similar stability properties.
Received June 15, 1993 相似文献
15.
Jean-Claude Yakoubsohn 《Numerical Algorithms》1994,6(1):63-88
We give a practical version of the exclusion algorithm for localizing the zeros of an analytic function and in particular of a polynomial in a compact of . We extend the real exclusion algorithm to a Jordan curve and give a method which excludes discs without any zero. The result of this algorithm is a set of discs arbitrarily small which contains the zeros of the analytic function. 相似文献
16.
We consider one of the crucial problems in solving polynomial equations concerning the construction of such initial conditions
which provide a safe convergence of simultaneous zero-finding methods. In the first part we deal with the localization of
polynomial zeros using disks in the complex plane. These disks are used for the construction of initial inclusion disks which,
under suitable conditions, provide the convergence of the Gargantini-Henrici interval method. They also play a key role in
the convergence analysis of the fourth order Ehrlich-Aberth method with Newton's correction for the simultaneous approximation
of all zeros of a polynomial. For this method we state the initial condition which enables the safe convergence. The initial
condition is computationally verifiable since it depends only on initial approximations, which is of practical importance. 相似文献
17.
《Journal of Computational and Applied Mathematics》1998,91(1):123-135
The choice of initial conditions ensuring safe convergence of the implemented iterative method is one of the most important problems in solving polynomial equations. These conditions should depend only on the coefficients of a given polynomial P and initial approximations to the zeros of P. In this paper we state initial conditions with the described properties for the Wang-Zheng method for the simultaneous approximation of all zeros of P. The safe convergence and the fourth-order convergence of this method are proved. 相似文献
18.
L. Pasquini 《Numerische Mathematik》2000,86(3):507-538
Summary. A general method for approximating polynomial solutions of second-order linear homogeneous differential equations with polynomial
coefficients is applied to the case of the families of differential equations defining the generalized Bessel polynomials,
and an algorithm is derived for simultaneously finding their zeros. Then a comparison with several alternative algorithms
is carried out. It shows that the computational problem of approximating the zeros of the generalized Bessel polynomials is
not an easy matter at all and that the only algorithm able to give an accurate solution seems to be the one presented in this
paper.
Received July 25, 1997 / Revised version received May 19, 1999 / Published online June 8, 2000 相似文献
19.
Numerical splitting of a real or complex univariate polynomial into factors is the basic step of the divide-and-conquer algorithms for approximating complex polynomial zeros. Such algorithms are optimal (up to polylogarithmic factors) and are quite promising for practical computations. In this paper, we develop some new techniques, which enable us to improve numerical analysis, performance, and computational cost bounds of the known splitting algorithms. In particular, we study a Chebyshev-like modification of Graeffe's lifting iteration (which is a basic block of the splitting algorithms, as well as of several other known algorithms for approximating polynomial zeros), analyze its numerical performance, compare it with Graeffe's, prove some results on numerical stability of both lifting processes (that is, Graeffe's and Chebyshev-like), study their incorporation into polynomial root-finding algorithms, and propose some improvements of Cardinal's recent effective technique for numerical splitting of a polynomial into factors. Our improvement relies, in particular, on a modification of the matrix sign iteration, based on the analysis of some conformal mappings of the complex plane and of techniques of recursive lifting/recursive descending. The latter analysis reveals some otherwise hidden correlations among Graeffe's, Chebyshev-like, and Cardinal's iterative processes, and we exploit these correlations in order to arrive at our improvement of Cardinal's algorithm. Our work may also be of some independent interest for the study of applications of conformal maps of the complex plane to polynomial root-finding and of numerical properties of the fundamental techniques for polynomial root-finding such as Graeffe's and Chebyshev-like iterations. 相似文献
20.
William W. Hager 《Numerische Mathematik》1986,50(3):253-261
Summary We present an algorithm to evaluate a polynomial at uniformly spaced points on a circle in the complex plane. As an application of this algorithm, a procedure is developed which gives a starting point for the Jenkins-Traub algorithm [5, 6] to compute the zeros of a polynomial.This work was supported by National Science Foundation grants DMS-8401758 and DMS-8520926 and Air Force Office of Scientific Research grant AFOSR-ISSA-860091 相似文献