a third-order newton-type method to solve systems of nonlinear equations - m.t. darvishi, a. barati

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  • 8/16/2019 A Third-Order Newton-type Method to Solve Systems of Nonlinear Equations - M.T. Darvishi, A. Barati

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    See discussions, stats, and author profiles for this publication at:https://www.researchgate.net/publication/220564348

    A third-order Newton-type method to

    solve systems of nonlinear equations

     ARTICLE  in  APPLIED MATHEMATICS AND COMPUTATION · APRIL 2007

    Impact Factor: 1.55 · DOI: 10.1016/j.amc.2006.08.080 · Source: DBLP

    CITATIONS

    62

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    2 AUTHORS:

    M. T. Darvishi

    Razi University

    85 PUBLICATIONS  917 CITATIONS 

    SEE PROFILE

    Ali Barati

    Razi University

    10 PUBLICATIONS  208 CITATIONS 

    SEE PROFILE

    All in-text references underlined in blue are linked to publications on ResearchGate,

    letting you access and read them immediately.

    Available from: M. T. Darvishi

    Retrieved on: 26 February 2016

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  • 8/16/2019 A Third-Order Newton-type Method to Solve Systems of Nonlinear Equations - M.T. Darvishi, A. Barati

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    A third-order Newton-type method to solve systemsof nonlinear equations

    M.T. Darvishi   *, A. Barati

    Department of Mathematics, Razi University, Kermanshah 67149, Iran

    Abstract

    In this paper, we present a third-order Newton-type method to solve systems of nonlinear equations. In the first we

    present theoretical preliminaries of the method. Secondly, we solve some systems of nonlinear equations. All test problems

    show the third-order convergence of our method.

     2006 Elsevier Inc. All rights reserved.

    Keywords:  Systems of nonlinear equations; Newton-type method; Third-order convergence

    1. Introduction

    In recent papers  [4,5]   a new family of third-order convergence methods have been obtained, by using

    an integral interpolation of Newton’s method to solve equation  f (x) = 0. There has been another approach

    based on the Adomian decomposition method on developing iterative method to solve the equation   f (x) =

    0 (see [3]).

    Recently, there has been some progress on Newton-type methods with cubic convergence that do not

    require the computation of second derivatives [6]. Chun [2] by improving Newton–Raphson method presented

    a new iterative method to solve nonlinear equations. His work is based on modification of the Abbasbandy’s

    proposal [1]  on improving the order of accuracy of Newton–Raphson method. Frontini and Sormani [4]  pre-

    sented a third-order iterative method for solving systems of nonlinear equations.

    In this paper, we construct a high order iterative method based on Adomian decomposition method tosolve the systems of nonlinear equations. This paper is organized as follows: In the next section we introduce

    an iterative method based on Adomian decomposition method to solve  f (x) = 0, this method introduced by

    Chun [2]. In Section 3  we extend the Chun’s method to solve systems of nonlinear equations. In that section

    we state and prove a theorem that shows the cubic convergence of the method. Numerical results are in Sec-

    tion 4. Finally, the paper is concluded is Section  5.

    0096-3003/$ - see front matter    2006 Elsevier Inc. All rights reserved.

    doi:10.1016/j.amc.2006.08.080

    * Corresponding author.

    E-mail address:  [email protected] (M.T. Darvishi).

    Applied Mathematics and Computation 187 (2007) 630–635

    www.elsevier.com/locate/amc

    https://www.researchgate.net/publication/223256799_Third-order_methods_from_quadrature_formulae_for_solving_systems_of_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/234796232_Iterative_methods_improving_Newton's_method_by_the_decomposition_method?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/234796232_Iterative_methods_improving_Newton's_method_by_the_decomposition_method?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/257194272_On_Newton-type_methods_with_cubic_convergence?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/257194272_On_Newton-type_methods_with_cubic_convergence?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/222139117_A_new_iterative_method_for_solving_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttp://-/?-https://www.researchgate.net/publication/223256799_Third-order_methods_from_quadrature_formulae_for_solving_systems_of_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/222139117_A_new_iterative_method_for_solving_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/222139117_A_new_iterative_method_for_solving_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttp://-/?-http://-/?-http://-/?-mailto:[email protected]://www.researchgate.net/publication/223256799_Third-order_methods_from_quadrature_formulae_for_solving_systems_of_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/223256799_Third-order_methods_from_quadrature_formulae_for_solving_systems_of_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/257194272_On_Newton-type_methods_with_cubic_convergence?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/234796232_Iterative_methods_improving_Newton's_method_by_the_decomposition_method?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/223117627_Some_variant_of_Newton's_method_with_third-order_convergence?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/222139117_A_new_iterative_method_for_solving_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzhttps://www.researchgate.net/publication/222139117_A_new_iterative_method_for_solving_nonlinear_equations?el=1_x_8&enrichId=rgreq-47a72c04-5b0d-4973-a26e-fc2257d54ecf&enrichSource=Y292ZXJQYWdlOzIyMDU2NDM0ODtBUzo5OTA5MDM5NDI1NTM4N0AxNDAwNjM2Mzk5ODkzmailto:[email protected]://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-http://-/?-

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    2. Description of an iterative method

    Consider the nonlinear equation

     f ð xÞ ¼ 0;   ð1Þ

    we assume that f (x) has a simple root a  and  c  is an initial guess sufficiently close to a. Let us convert the non-

    linear equation (1) into the following coupled system:

     f ðcÞ þ f 0ðcÞð x  cÞ þ g ð xÞ ¼ 0;   ð2Þ

     g ð xÞ ¼ f ð xÞ  f ðcÞ  f 0ðcÞð x  cÞ:   ð3Þ

    Eq. (2) can be rewritten in the following form:

     x ¼  c þ N ð xÞ;   ð4Þ

    where  c ¼  c     f ðcÞ f 0ðcÞ

     and  N ð xÞ ¼   g ð xÞ f 0ðcÞ

     is a nonlinear function.

    The Adomian decomposition method looks for a solution having the series form

     x ¼ X1

    n¼0

     xn   ð5Þ

    and the nonlinear function is decomposed as

     N ð xÞ ¼X1n¼0

     An;   ð6Þ

    where the  Ans are functions called the Adomian’s polynomials depending on  x0, x1, . . . , xn  given by

     An  ¼  1

    n!

    dn

    dkn   N 

    X1i¼0

    ki xi

    !" #k¼0

    ;   n ¼  0; 1; . . .

    the first few polynomials are given by

     A0  ¼  N ð x0Þ;

     A1  ¼  x1 N 0ð x0Þ;

     A2  ¼  x2 N 0ð x0Þ þ

     1

    2 x21 N 

    00ð x0Þ:

    Upon substituting (5) and (6) into (4) yieldsX1n¼0

     xn  ¼  c þX1n¼0

     An:   ð7Þ

    It follows from (7) that

     x0  ¼  c;

     x1  ¼  A0;

     xnþ1  ¼  An;   n ¼  0; 1; . . .

    An elementary calculation shows that

     A0  ¼  N ð x0Þ ¼  g ð x0Þ

     f 0ðcÞ ¼

     f ð x0Þ

     f 0ðcÞ  ;

     N 0ð x0Þ ¼ 1  f ð x0Þ

     f 0ðcÞ  ;

     A1  ¼  x1 N 0ð x0Þ ¼ A0 N 

    0ð x0Þ ¼  f ð x0Þ

     f 0

    ðcÞ

     þ f ð x0Þ f 

    0ð x0Þ

    ð f 0ðcÞÞ2

      :

    M.T. Darvishi, A. Barati / Applied Mathematics and Computation 187 (2007) 630–635   631

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    Note that x  is approximated by

     X m  ¼  x0 þ x1 þ þ xm  ¼  x0 þ A0 þ A1 þ þ Am1;

    where limm!1 X m = x.

    For  m = 0

     x   X 0  ¼  x0  ¼  c  ¼  c   f 

    ðc

    Þ f 0ðcÞ;

    which yields the Newton method

     xnþ1 ¼  xn  f ð xnÞ

     f 0ð xnÞ:

    For  m = 1

     x   X 1  ¼  x0 þ x1  ¼  c þ A0  ¼  c  f ðcÞ

     f 0ðcÞ 

     f ð x0Þ

     f 0ðcÞ  ;

    which produces the following iteration scheme

     xnþ1 ¼  xn   f ð xnÞ

     f 0ð xnÞ  f ð x

    nþ1Þ

     f 0ð xnÞ  ;   ð8Þ

    where

     xnþ1 ¼  xn  f ð xnÞ

     f 0ð xnÞ:

    3. The  n-dimensional case

    We know Newton iterative method for the nonlinear system F(x) = 0 where F  :  X   Rn ! Rn is defined by

     xnþ1 ¼  xn  F0ð xnÞ

    1Fð xnÞ;   ð9Þ

    where  F 0(xn) is the Jacobian matrix in point  xn.

    We rewrite Eq. (8) to solve the nonlinear system F(x) = 0, this produces the following iteration scheme:

     xnþ1 ¼  xn  F0ð xnÞ

    1ðFð xnÞ þ Fð xnþ1ÞÞ;   ð10Þ

    where

     xnþ1 ¼  xn  F0ð xnÞ

    1Fð xnÞ:

    We call iteration scheme (10) as the modified Newton method (mNm) to solve systems of nonlinear equations.

    Theorem 1.   Let   F   : X   Rn ! Rn, is k-time Fré chet differentiable in a convex set  X  containing the root  a  of F(x) = 0. The modified Newton’s method (mNm)  (10)  has order of convergence three.

    Proof.   For any  x, xn

     2 X, we write the Taylor’s expansion for F:

    Fð xÞ ¼ Fð xnÞ þ F0ð xnÞð x  xnÞ þ

     1

    2!F00ð xnÞð x  xnÞ

    2 þ 1

    3!Fð3Þð xnÞð x  xnÞ

    3 þ þ 1

    k !Fðk Þð xnÞða  xnÞ

    k  þ

    If  a  be root of system F(x) = 0, we have:

    FðaÞ ¼ Fð xnÞ þ F0ð xnÞða  xnÞ þ

     1

    2!F00ð xnÞða  xnÞ

    2 þ 1

    3!Fð3Þð xnÞða  xnÞ

    3 þ þ 1

    k !Fðk Þð xnÞða  xnÞ

    k þ

    Defining  en

     = xn  a  we have:

    0 ¼  Fð xnÞ  F0ð xnÞen þ

     1

    2!F00ð xnÞe

    2n 

     1

    3!Fð3Þð xnÞe

    3n þ þ ð1Þ

    k  1

    k !Fðk Þð xnÞe

    k n þ

    632   M.T. Darvishi, A. Barati / Applied Mathematics and Computation 187 (2007) 630–635

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    hence

    Fð xnÞ ¼ F0ð xnÞen 

     1

    2!F00ð xnÞe

    2n þ

     1

    3!Fð3Þð xnÞe

    3n þ ð1Þ

    k  1

    k !Fðk Þð xnÞe

    k n þ

    For  k  = 3

    Fð xnÞ ¼ F0ð xnÞen   12!

    F00ð xnÞe2n þ  13!Fð3Þð xnÞe3n þ Oðke4nkÞ ð11Þ

    if we multiply Eq. (11) from left by F0

    (xn)1 then we have:

    F0ð xnÞ1

    Fð xnÞ ¼  F0ð xnÞ

    1F0ð xnÞen 

     1

    2!F0ð xnÞ

    1F00ð xnÞe

    2n þ

     1

    3!F0ð xnÞ

    1Fð3Þð xnÞe

    3n þ Oðke

    4nkÞ

    or

    F0ð xnÞ1

    Fð xnÞ ¼  en  1

    2!F0ð xnÞ

    1F00ð xnÞe

    2n þ

     1

    3!F0ð xnÞ

    1Fð3Þð xnÞe

    3n þ Oðke

    4nkÞ ð12Þ

    from iterative scheme (10) we have:

     xnþ1  xn  ¼ F0

    ð xnÞ

    1

    ðFð xnÞ þ Fð xn  F0

    ð xnÞ

    1

    Fð xnÞÞÞ;

    then

    enþ1  ¼  en  F0ð xnÞ

    1Fð xnÞ  F

    0ð xnÞ1

    Fð xn  F0ð xnÞ

    1Fð xnÞÞ:   ð13Þ

    By substituting (12) into (13) we obtain:

    enþ1  ¼  en    en  1

    2!F0ð xnÞ

    1F00ð xnÞe

    2n þ

     1

    3!F0ð xnÞ

    1Fð3Þð xnÞe

    3n þ Oðke

    4nkÞ

     F0ð xnÞ

    1Fð xn  F

    0ð xnÞ1

    Fð xnÞÞ:

    By Taylor’s expansion for  F(xn  F

    0

    (xn)1F(x

    n)) around x

    n we have:

    enþ1  ¼  1

    2!

    F0ð xnÞ1

    F00ð xnÞe2n 

     1

    3!

    F0ð xnÞ1

    Fð3Þð xnÞe3n

    þ Oðke4nkÞ  F0ð xnÞ

    1Fð xnÞ  F

    0ð xnÞF0ð xnÞ

    1Fð xnÞ

    þ 1

    2!F00ð xnÞðF

    0ð xnÞ1

    Fð xnÞÞ2

     1

    3!Fð3Þð xnÞðF

    0ð xnÞ1

    Fð xnÞÞ3 þ Oðke4nkÞ

    enþ1  ¼  1

    2!F0ð xnÞ

    1F00ð xnÞe

    2n 

     1

    3!F0ð xnÞ

    1Fð3Þð xnÞe

    3n

     1

    2!F0ð xnÞ

    1F00ð xnÞ   en 

     1

    2!F0ð xnÞ

    1F00ð xnÞe

    2n þ Oðke

    3nkÞ

    2

    þ 1

    3!

    F0ð xnÞ1

    Fð3Þð xnÞ   en  1

    2!

    F0ð xnÞ1

    F00ð xnÞe2n þ Oðke

    3nkÞ

    3

    þ Oðke4nkÞ

    after some manipulations we obtain:

    enþ1  ¼ 1

    2½F0ð xnÞ

    1F00ð xnÞ

    2e3n þ Oðke

    4nkÞ:   ð14Þ

    This shows the third-order convergence of the method. Hence, the proof is completed.   h

    4. Numerical examples

    In this section we solve three systems of nonlinear equations. The following tables show the number of iter-

    ations to receive the required solution, as these tables show the order of convergence is three. For all test prob-

    lems the stop criteria is kF(xn)k < 1015.

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    Example 1.  Consider the following system of nonlinear equations

     x21 þ x22 þ x

    23  ¼  1;

    2 x21 þ x22  4 x3  ¼  0;

    3 x2

    1

      4 x22

     þ x23

     ¼  0:

    We solve this system by mNm using initial approximation x0 = (0.5,0.5,0.5)T. Table 1 shows the values of  x1,

    x2 and  x3. We can see the third-order convergence of the approximations.

    Example 2.  The second test problem is taken as

     x21 þ 3 log x1  x22  ¼  0;

    2 x21  x1 x2  5 x1 þ 1 ¼  0:

    Its initial approximation is x0 = (3.4,2.2)T.  Table 2 shows  xi s approximations. We obtain the required solu-

    tions only after four iterations.

    Example 3.  The last example has the following form:

     x1 þ 2 x2  3 ¼  0

    2 x21 þ x22  5 ¼  0:

    The initial approximation of the solution is x0 = (1.5,1.0)T. Table 3 shows the approximation of the solution.

    As we can see from this table, the convergency order is three.

    Table 2

    Approximations of  x i s for Example 2

    n x1   x2

    1 3.48730136242187 2.26152939389406

    2 3.48744278764273 2.26162863055323

    3 3.48744278764295 2.26162863055359

    4 3.48744278764295 2.26162863055359

    Table 3

    Approximations of  x i s for Example 3

    n x1   x2

    1 1.48750000000000 0.75625000000000

    2 1.48803387165546 0.75598306417227

    3 1.48803387171258 0.75598306414371

    4 1.48803387171258 0.75598306414371

    Table 1

    Approximations of  x i s for Example 1

    n x1   x2   x3

    1 0.67625000000000 0.62300000000000 0.34325000000000

    2 0.69827680505888 0.62852407959171 0.34256418976030

    3 0.69828860997151 0.62852429796021 0.34256418968957

    4 0.69828860997151 0.62852429796021 0.34256418968957

    634   M.T. Darvishi, A. Barati / Applied Mathematics and Computation 187 (2007) 630–635

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    5. Conclusion

    In this paper, we introduced a cubic convergence iterative method to solve systems of nonlinear equations.

    This method has simple implementation. As test examples show there is a fast convergence to receive the solu-

    tion with a required accuracy.

    References

    [1] S. Abbasbandy, Improving Newton–Raphson method for nonlinear equations by modified Adomian decomposition method, Appl.

    Math. Comput. 145 (2003) 887–893.

    [2] Ch. Chun, A new iterative method for solving nonlinear equations, Appl. Math. Comput. 178 (2) (2006) 415–422.

    [3] Ch. Chun, Iterative methods improving Newton’s method by the decomposition method, Comput. Math. Appl. 50 (2005) 1559–1568.

    [4] M. Frontini, E. Sormani, Third-order methods from quadrature formulae for solving systems of nonlinear equations, Appl. Math.

    Comput. 149 (2004) 771–782.

    [5] M. Frontini, E. Sormani, Some variants of Newton’s method with third-order convergence, Appl. Math. Comput. 140 (2003) 419–426.

    [6] H.H.H. Homeier, On Newton-type methods with cubic convergence, J. Comput. Appl. Math. 176 (2005) 425–432.

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