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 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
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2 AUTHORS:
M. T. Darvishi
Razi University
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Ali Barati
Razi University
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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.
M.T. Darvishi, A. Barati / Applied Mathematics and Computation 187 (2007) 630–635 633
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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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