Numerical solution of fuzzy hybrid differential equation by third order runge kutta nystrom method

Mathematical Theory and Modeling www.iiste.org
ISSN 2224-5804 (Paper) ISSN 2225-0522 (Online)
Vol.2, No.4, 2012

Numerical solution of Fuzzy Hybrid Differential Equation by
Third order Runge Kutta Nystrom Method
N.Saveetha 1* Dr.S.Chenthur Pandian 2
1. Department of Mathematics, Vivekanandha College of Technology for women, Affiliated to
AnnaUniversity of Technology Coimbatore, Tamil Nadu, India.
2. Principal, Dr Mahalingam College of Engineering and Technology, Affiliated to Anna University of
Technology Coimbatore, Tamil Nadu, India
* E-mail of the corresponding author: saveesethu@gmail.com

Abstract
In this paper we study numerical method for hybrid fuzzy differential equations by an application of
Runge–Kutta Nystrom method of order three. Here we state a convergence result and give a numerical
example to illustrate the theory. This method is discussed in detail and this is followed by a complete error
analysis.
Keywords: Hybrid systems; Fuzzy differential equations; Runge–Kutta Nystrom method

1. Introduction
Hybrid systems are devoted to modeling, design, and validation of interactive systems of computer
programs and continuous systems. That is, control systems that are capable of controlling complex systems
which have discrete event dynamics as well as continuous time dynamics can be modeled by hybrid
systems. The differential systems containing fuzzy valued functions and interaction with a discrete time
controller are named hybrid fuzzy differential systems.
In this article we develop numerical methods for solving hybrid fuzzy differential equations by an
application of the Runge–Kutta Nystrom method [6]. In Section 2 we list some basic definitions for fuzzy
valued functions. Section 3 reviews hybrid fuzzy differential systems. Section 4 contains the Runge–Kutta
Nystrom method for approaching hybrid fuzzy differential equations. Section 5 contains a numerical
example to illustrate the theory.

2. Preliminaries
By we denote the set of all real numbers. A fuzzy number is a mapping u: [0, 1]
with the following properties:
(a) u is upper semicontinous,
(b) u is fuzzy convex, i.e., u ( for all x, y , [0,1],
(c) is normal, i.e., for which
(d) Supp u = { is the support of and its closure cl (supp ) is compact.
Let be the set of all fuzzy number on r.The r-level set of a fuzzy number denoted
by , is defined as

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Vol.2, No.4, 2012

=

It is clear that the r- level set of a fuzzy number is a closed and bounded interval ,
where denotes the left-hand end point of and denotes the right- hand side end point of
.since each can be regarded as a fuzzy number is defined by

Remark 2.1
Let X be the Cartesian product of universes , and be n fuzzy numbers in
respectively. f is a mapping from X to a universe Y,
.Then the extension principle allows us to define a fuzzy set B in Y by
, where

Where is the inverse of .For n=1, the extension principle, of course, reduces to
}

Where

According to Zadeh’s extension principle, operation of addition on € is defined by

and scalar multiplication of a fuzzy number is given by

Where The Hausdorff distance between fuzzy numbers given by

It is easy to see that D is a metric in € and has the following properties

(i) D(u w,v w)=D(u,v), u,v,w
(ii) D(k u,k v)= D(u,v), k , u,v
(iii) D(u v,w e) D(u,w) + D(v,e), u,v,w,e
(iv) (D, €) is a complete metric space.

Next consider the initial value problem (IVP)

(2.1)

Where f is continuous mapping from into and € with r level sets

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Vol.2, No.4, 2012

The extension principle of Zadeh leads to the following definition of f (t, x) when x = x (t) is a fuzzy
number

It follows that
Where

Theorem 2.1
Let f satisfy
Where g: is a continuous mapping such that is non decreasing and the initial value
problem

has a solution on for > 0 and that = 0 is the only solution of (2.2) for Then the fuzzy
initial value problem (2.1) has a unique solution.

3. The hybrid fuzzy differential system
Consider the hybrid fuzzy differential equation

Where denotes the seikkala derivative, 0

, [€,€].

To be specific the system will be as follows

With respect to the solution of (3.1), we determine the following function:

We note that the solutions of (3.1) are piecewise differentiable in each interval for t

[tk,tk+1] for a fixed xk € and k=0,1,2,….

Therefore we may replace (3.1) by an equivalent system

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Vol.2, No.4, 2012

(3.2)

which possesses a unique solution ( which is a fuzzy function. That is for each t, the pair

is a fuzzy number, where, are respectively the solutions of the parametric

form given by

(3.3)

4. The Runge–Kutta Nystrom method
In this section ,for a hybrid fuzzy differential equation (3.1) we develop a Runge kutta Nystrom method of
order three via an application of the Runge kutta Nystrom method for fuzzy differential equation in
[6].We assume that the existence and the uniqueness of the solutions of (3.1) hold for each [ .
For a fixed r, to integrate the system (3.3) in [ we replace each interval
by a set of discrete equally spaced grid points at which the exact solution
is approximated by some ( , .
For the chosen grid points on [

, ,

Let .

and ( , ) may be denoted respectively by and

.We allow the to vary over the [ so that the may be comparable.To

develop the Runge kutta method of order three for (3.1),we follow[6] and define

Where are constants and

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Vol.2, No.4, 2012

Where in Runge kutta method of order three

+

+

Next we define

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Vol.2, No.4, 2012

The exact solution at is given by

The approximate solution is given by

(4.1)

Theorem 4.1

Consider the systems (3.2) and (4.1), for a fixed and

5. Numerical example
Before illustrating the numerical solution of a hybrid fuzzy IVP, first we recall the fuzzy IVP:

(5.1)

The exact solution is given by

We see that

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Vol.2, No.4, 2012

By the Runge kutta Nystrom

method with N = 2 in [6],(5.1) gives

where

Comparing the Euler in [10] and Runge kutta Nystrom method in [6] we see that Runge-kutta is much
closer to the true solution.

Example 1
Next consider the following hybrid fuzzy IVP

(5.2)

where

In(5.2) , x(t)+m(t)λk(x(tk)) is a continuous function of t, x, and λk(x(tk)). Therefore by Example 6.1
of Kaleva [5] and Theorem 4.2 of Buckley and Feuring [2] for each k=0,1,2,…, the fuzzy IVP

has a unique solution on [ ]. To numerically solve the hybrid fuzzy IVP (5.2) we will apply the

Runge–Kutta method for hybrid fuzzy differential equations from Section 4 with N=2 to obtain y1,2(r)

approximating x(2.0;r). Let be given by

where

is given by

Since the exact solution of (5.4) for t [1,1.5] is ,

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Vol.2, No.4, 2012

Then x(1.5;1) is approximately 5.29 and y1,1(1) is

approximately 5.248.Since the exact solution of (5.4)for

t [1.5,2] is ,

, Then x(2.0;1) is approximately 9.68 and y1,2(1) is

approximately 9.65 .These observations are summarized in Table 5.1 For additional comparison, Fig 5.1
shows the graphs of x(2.0), y1,2, and the corresponding Euler approximation.

References
[1] Abbasbandy.S and Allahviranloo.T (2002), “Numerical Solutions of fuzzy differential equations”,
Mathematical and computational applications 7 pp 41-52
[2] Buckley J.J and Feuring T.,(2000), “Fuzzy differential equations”, Fuzzy Sets and Systems 110 , pp.
43–54.
[3] Friedman M.Ma and .Kandel.A, (1999) “Numerical Solutions of fuzzy differential equations,” Fuzzy
sets and systems 105(1999),pp 133-138.
[4] Goetschel.R and Voxman.W.,(1986), “ Elementary fuzzy calculus”, Fuzzy Sets and Systems 18 , pp.
31–43.
[5] Kaleva.O, (1987),”Fuzzy differential equations”, Fuzzy Sets and Systems 24 , pp. 301–317.
[6] Kanagarajan.K and Sampath.M, (2010)“Runge kutta Nystrom method of order three for solving fuzzy
differential equations”,Computational methods in Applied Mathematics, Vol 10(2),pp 195-203.
[7] Nirmala.V, Chenthur Pandian.S, (2011)“Numerical solution of fuzzy differential equation by fourth
order runge kutta method with higher order derivative approximations” European Journal of Scientific
Research Vol 62 No 2 pp 198-206.
[8] Nirmala.V, Saveetha.N, Chenthur Pandian.S, (2010) “Numerical solution of fuzzy differential equation
by Runge kutta method with higher order derivative approximations” Proceedings of the international
conference on emerging trends in mathematics and computer applications,MEPCO Schlenk Engineering
college Sivakasi.Dec 16-18, PP 131-134(ISBN:978-81-8424-649-0)
[9] Palligkinis S.Ch, Papageorgiou.G, Famelis I.TH.,(2009) “Runge-Kutta methods for fuzzy differential
equations”, Applied Mathematics and Computation 209 pp 97-105.
[10] Pederson.S and Sambandham.M.,(2007) “Numerical solution to hybrid fuzzy systems”,
Mathematical and Computer Modelling 45 , pp. 1133–1144.
[11] Pederson.S and Sambandham.M.,(2006) “The Runge kutta method for hybrid fuzzy differential
equations”, Nonlinear Analysis: Hybrid Systems 2 pp 626–634
[12] Sambandham.M, (2002) “Perturbed Lyaponav-like functions and hybrid fuzzy diferrential
equations”,International journal of hybrid systems 2),pp.23-34.
[13] Saveetha.N, Nirmala.V, Chenthur Pandian.S, (2011) “The Runge kutta method of order three for
hybrid fuzzy differential equations” European Journal of Scientific Research Vol 62 No 3 pp 335-343
[14] Seikkala.S, (1987)“On the fuzzy initial value problem”,Fuzzy sets and systems 24 ,pp.319-330.
[15] Wu C.-X. and M. Ma., (1991), “Embedding problem of fuzzy number space: Part I”, Fuzzy Sets and
Systems 44 , pp. 33–38.

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Figure 5.1. Comparison of Euler and Runge Kutta Nystrom method with the Exact Solution

Table 5.1:

Comparison of Exact and Approximate Solution

At t=1.5

Exact solution Approximate solution
r

1 5.290221725 5.290221725 5.248236760 5.248236760
0.8 5.025710639 5.422477268 4.985824922 5.379442679
0.6 4.761199553 5.554732811 4.723413084 5.510648598
0.4 4.496688467 5.686988354 4.461001246 5.641854517
0.2 4.23217738 5.819243898 4.198589408 5.773060436
0 3.967666294 5.95149941 3.936177570 5.904266355

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Vol.2, No.4, 2012

At t=2

Exact solution Approximate solution
r

1 9.676975672 9.676975672 9.653510761 9.653510761
0.8 9.193126888 9.918900064 9.170835223 9.89484853
0.6 8.709278105 10.16082446 8.688159685 10.13618629
0.4 8.225429321 10.40274885 8.205484147 10.37752406
0.2 7.741580538 10.64467324 7.722808609 10.61886183
0 7.257731754 10.88659763 7.240133071 10.86019960

Error for different values of t

r t=1 t=1.5 t=2

1 0.009514468 0.041984965 0.023464911
0.8 0.009038745 0.039885717 0.022291665
0.6 0.008563022 0.037786469 0.021118420
0.4 0.008087298 0.035687221 0.019945174
0.2 0.007611575 0.033587972 0.018771929
0 0.007135851 0.031488724 0.017598683

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Numerical solution of fuzzy hybrid differential equation by third order runge kutta nystrom method

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