4_xxx_ibis.dvi EUROPEAN JOURNAL OF PURE AND APPLIED MATHEMATICS Vol. 4, No. 2, 2011, 129-141 ISSN 1307-5543 – www.ejpam.com Applications of Fractional Differential Transform Method to Fractional Differential-Algebraic Equations Birol İbi̧s1,∗, Mustafa Bayram2, A. Göksel Ağargün3 1 Department of Main Sciences, Turkish Air Force Academy, Istanbul,Turkey 2 Mathematical Engineering, Faculty of Chemical and Metallurgical Engineering, Yıldız Technical University, Istanbul,Turkey 3 Department of Mathematics, Faculty of Art and Sciences, Yıldız Technical University, Istanbul,Turkey Abstract. In this paper, we implement fractional differential transform method (FDTM), which is a semi analytical numerical technique, to fractional differential-algebraic equations (FDAEs). The frac- tional derivatives are described in the Caputo sense. The method provides the solution in the form of a rapidly convergent series. The method is illustrated by four examples of FDAEs and solutions are ob- tained. Comparisons are made between fractional differential transform method (FDTM), Homotopy Analysis Method (HAM) and the exact solutions. The results reveal that the proposed method is very effective and simple. 2000 Mathematics Subject Classifications: 4A08,34K28,34B05,34B15,65L10,74S30 Key Words and Phrases: Fractional Differential Transform Method (FDTM), Fractional Differential- Algebraic Equations (FDAEs), Caputo , Homotopy Analysis Method (HAM) 1. Introduction Fractional differential equations (FDEs) have been succesfully modelled for many physical and engineering phenomena such as seismic analysis, rheology, fluid flow, viscous damping, viscoelastic materials and polymer physics [9, 2, 31, 16, 32, 3]. Most nonlinear FDEs don’t have exact analytic solutions, therefore approximation and numerical techniques must be used. Some of the recent analytic methods for solving nonlinear problems include the Ado- mian decomposition method (ADM) [12, 11, 30, 38, 35, 14], variational iteration method (VIM) [18, 19, 42, 36, 33], homotopy analysis method (HAM) [34, 13, 40, 37, 27] and frac- tional method [17]. Among these solution techniques, the VIM and the ADM are the most clear methods of solution of FDEs for providing instant and visible symbolic terms of ana- lytic solutions, as well as numerical approximate solutions to nonlinear differential equations without linearization or discretization. ∗Corresponding author. Email address: bibis�hho.edu.tr (B. İbi̧s) http://www.ejpam.com 129 c© 2011 EJPAM All rights reserved. B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 130 Many physical problems are governed by a system of differential-algebraic equations (DAEs), and the solution of these equations has been a subject of many investigators in recent years. Although many exact solutions for linear DAEs has been found, in general, there exists no method that yields an exact solution for nonlinear DAEs. Numerical approaches for ap- proximating solutions of DAEs have been presented [39, 29, 28, 6, 5, 4, 8, 24, 25, 7, 10, 15]. Recently, many important mathematical models can be expressed in terms of differential- algebraic equations of fractional order. Homotopy analysis method was first introduced by Liao [34], who employed the basic ideas of the homotopy in topology to propose a general analytic method for nonlinear problems. Zurigat, Momani and Alawneh [26] applied this method for fractional differential-algebraic equations (FDAEs). The differential transform method (DTM) was first applied in the engineering domain in [20]. The DTM is numerical method based on the Taylor series expansion which constructs an analytical solution in the form of a polynomial. The traditional high order Taylor series method requires symbolic computation. However, the DTM obtains a polynomial series so- lution by means of an iterative procedure. Arikoglu and Ozkol implement a new analytical technique for the field of fractional calculus, for solving fractional type differential equations that will be named as Fractional Differential Transform Method (FDTM)[1]. In this paper, fractional differential transform method (FDTM) is applied to solve fractional differential- algebraic equations (FDAEs) of form D αi ∗ x i(t) = f (t, x1, x2, . . . , xn, x ′1, x ′2, . . . , x ′n), i = 1,2,3, . . . , n− 1, t ≥ 0, 0< αi ≤ 1 (1) g(t, x1, x2, . . . , xn) = 0 (2) subject to the initial conditions x i(0) = ai , i = 1,2, . . . , n (3) 2. Basic Definitions There are several definitions of a fractional derivative of order α > 0 [17, 22].e.g.Riemann- Liouville, Grunwald-Letnikow, Caputo and Generalized Functions Approach. The most com- monly used definitions are the Riemann-Liouville and Caputo. We give some basic definitions and properties of the fractional calculus theory which are used further in this paper. Definition 1. A real function f (x), x > 0, is said to be in the space Cµ, µ ∈ R if there exists a real number p > µ such that f (x) = x p f1(x), where f1(x) ∈ C[0,∞). Clearly Cµ < Cβ if β < µ. Definition 2. A function f (x), x > 0, is said to be in the space Cm µ , m ∈ N ∪ {0} if f (m) ∈ Cµ. Definition 3. The Riemann-Liouville fractional integral operator of order a α≥ 0 of a function, f ∈ Cµ,µ ≥ −1 is defined as [31] Jα f (x) = 1 Γ(α) ∫ x 0 (x − t)α−1 f (t)d t, α > 0, x > 0 (4) J0 f (x) = f (x) (5) B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 131 Properties of the operator Jα can be found in [41, 23, 21], we mention only the following: For f ∈ Cµ, µ ≥ −1, α,β ≥ 0 and γ > −1 JαJβ f (x) = Jα+β f (x) (6) JαJβ f (x) = Jβ Jα f (x) (7) Jαxγ = Γ(γ+ 1) Γ(α+ γ+ 1) xα+γ (8) The Riemann-Liouville derivative has certain disadvantages when trying to model real-world phenomena using fractional differential equations. Therefore, we will introduce a modified fractional differential operator proposed by Caputo’s work on the theory of viscoelasticity [22]. Definition 4. The fractional derivative of f (x) in the Caputo sense is defined as Dα∗ f (x) = J m−αDm f (x) = 1 Γ(m−α) ∫ x 0 (x − t)m−α−1 f (m)(t)d t, (9) for m− 1< α≤ m, m ∈ N, x > 0, f ∈ Cm −1. Also, we need here two of its basic properties. Lemma 1. If m− 1< α ≤ m, m ∈ N and f ∈ Cm µ , m ≥ −1, then Dα∗ J α f (x) = f (x) (10) JαDα∗ f (x) = f (x)− m−1 ∑ k=0 f (k)(0+) x k k! , x > 0 (11) 3. Fractional Differential Transform Method (FDTM) In this section, we introduce the fractional differential transform method used in this paper to obtain approximate analytical solutions for FDAEs in Eq.(1). This method has been developed in [1] as follows: The fractional differentiation in Riemann-Liouville sense is defined by Dα f (x) = 1 Γ(m−α) Dm �∫ x 0 (x − t)m−α−1 f (t)d t � (12) for m− 1≤ α < m, m ∈ N , x > 0. Let us expand the analytical and continuous function f (x) in terms of a fractional power series as follows: f (x) = ∞ ∑ k=0 F(k)x k β (13) B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 132 where β is the order of fraction and F(k) is the fractional differential transform of f (x) . In order to avoid fractional initial and boundary conditions, we define the fractional deriva- tive in the Caputo sense. The relation between the Riemann-Liouville operator and Caputo operator is given by Dα∗ f (x) = Dα f (x)− m−1 ∑ k=0 f (k)(0+) x k k! ! (14) Setting f (x) = f (x)− ∑m−1 k=0 f (k)(0+) xk k! in Eq.(12)and using Eq.(14), we obtain fractional derivative in the Caputo sense as follows: Dα∗ f (x) = 1 Γ(m−α) Dm   ∫ x 0 (x − t)m−α−1 f (t)− m−1 ∑ k=0 f (k)(0+) tk k! ! d t   (15) Since the initial conditions are implemented for the integer order derivatives, the transforma- tion of the initial conditions are defined as follows: F(k) = ( 1 (k/β)! h dk/β f (x) d xk/β i x=0 for k = 0,1,2, . . . , (αβ − 1) , k/β ∈ N+ 0 , k/β /∈ N+ (16) where, α is the order of fractional differential equation considered. The following theorems that can be deduced from Eqs.(12) and (13) are given below,for proofs and details see [1]. Theorem 1. if f (x) = g(x)± h(x), then F(k) = G(k)±H(k) Theorem 2. if f (x) = g(x)h(x), then F(k) = ∑k l=0 G(l)H(k− l) Theorem 3. if f (x) = g1(x)g2(x) · · · gn−1(x)gn(x), then F(k) = k ∑ kn−1=0 kn−1 ∑ kn−2=0 · · · k3 ∑ k2=0 k2 ∑ k1=0 G1(k1)G2(k2− k1) · · ·Gn−1(kn−1 − kn−2)Gn(k− kn−1) (17) Theorem 4. if f (x) = x p, then F(k) = δ(k− βp) where, δ(k) = ¨ 1 if k = 0 0 if k 6= 0 (18) Theorem 5. if f (x) = Dαg(x), then F(k) = Γ(α+1+k/β) Γ(1+k/β) G(k+αβ) Theorem 6. if f (x) = Dα1 g1(x)D α2 g2(x) · · ·D αn−1 gn−1(x)D αn gn(x), then F(k) = k ∑ kn−1=0 kn−1 ∑ kn−2=0 · · · k3 ∑ k2=0 k2 ∑ k1=0 Γ(α1 + 1+ k1/β) Γ(1+ k1/β) Γ(α2 + 1+ (k2− k1)/β) Γ(1+ (k2− k1)/β) · · · × Γ(αn+ 1+ (k− kn−1/β) Γ(1+ (k− kn−1/β) G1(k1 +α1β)G2(k2− k1 +α2β) · · ·Gn(k− kn−1 +αnβ) where βαi ∈ Z+ for i = 1,2, . . . , n. B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 133 4. Numerical Examples In order to demonstrate the effectiveness of the fractional differential transform method, we consider the following FDAEs. All the results are calculated by using the symbolic calculus software Maple. Example 1. We consider the following fractional differential-algebraic equations. Dα∗ x(t)− t y ′(t) + x(t)− (1+ t)y(t) = 0, 0< α≤ 1 (19) y(t)− sin(t) = 0 (20) with initial conditions as x(0) = 1, y(0) = 0 (21) For the special case when α = 1 the exact solution is x(t) = e−t + tsin(t), y(t) = sin(t). Eqs.(19)-(20) are transformed by using Theorems 1, 2, 4, 5 and Eq.(13) as follows: X (k+αβ) = Γ(1+ k/β) Γ(α+ 1+ k/β)   k ∑ l=0 � Γ(2+ l/β) Γ(1+ l/β) Y (l + β) + Y (l) � δ(k− l − β)− X (k)+ Y (k)   (22) Y (k) = ∞ ∑ i=0 (−1)i (2i+ 1)! δ(k− β(2i+ 1)) (23) where β is the unknown value of the fractions. Initial conditions in Eq.(21) are transformed by using Eq.(16) as follows: X (0) = 1, Y (0) = 0, X (k) = Y (k) = 0 for k = 1,2, . . . ,αβ − 1 (24) From Eqs.(22)-(24), X (k) and Y (k) are obtained for different values of α and using the inverse transformation in Eq.(13), x(t) and y(t) are evaluated.Numerical results with comparison to Ref. [26] is given in Table 1. Example 2. Consider the following fractional differential-algebraic equations. D α1 ∗ x(t)− x(t)− z(t)x(t) = 1 (25) D α2 ∗ z(t)− y(t) + x2(t) + z(t) = 0, 0< α1,α2 ≤ 1 (26) y(t)− x2(t) = 0 (27) with initial conditions as x(0) = y(0) = z(0) = 1 (28) For α1 = α2 = 1 the exact solution is x(t) = et , y(t) = e2t , z(t) = e−t . By using Theorems 1, 2, 4, 5 and Eq.(13), Eqs.(25)-(27) are transformed to, X (k+α1β1) = Γ(1+ k/β1) Γ(α1 + 1+ k/β1)  X (k)− k ∑ l=0 Z(l)X (k− l) + δ(k)   (29) B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 134Table 1: Numeri al results with omparison to Ref. [26℄ in Example 1 α = 0.5 α= 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 0.1 0.7642925 0.7642925 0.8492995 0.8492996 0.9148208 0.9148208 0.9148208 0.2 0.7545097 0.7545096 0.8016696 0.8016697 0.8584646 0.8584646 0.8584646 0.3 0.7903162 0.7903162 0.7979000 0.7978999 0.8294743 0.8294743 0.8294743 0.4 0.8524950 0.8524950 0.8250873 0.8250871 0.8260874 0.8260874 0.8260874 0.5 0.9323247 0.9323247 0.8760146 0.8760144 0.8462434 0.8462434 0.8462434 0.6 1.0242052 1.0242052 0.9454582 0.9454582 0.8875971 0.8875971 0.8875971 0.7 1.1237906 1.1237906 1.0290755 1.0290757 0.9475377 0.9475377 0.9475377 0.8 1.2273291 1.2273291 1.1229592 1.1229595 1.0232138 1.0232138 1.0232138 0.9 1.3313916 1.3313915 1.2234363 1.2234368 1.1115639 1.1115639 1.1115639 1.0 1.4327552 1.4327552 1.3269757 1.3269767 1.2093505 1.2093504 1.2093504 Z(k+α2β2) = Γ(1+ k/β2) Γ(α2 + 1+ k/β2)  Y (k)− k ∑ l=0 X (l)X (k− l)− Z(k)   (30) Y (k) = k ∑ l=0 X (l)X (k− l) (31) where β1 and β2 are the unknown values of the fractions and β = LC M(β1,β2). From Eq.(16), initial conditions in Eq.(28) can be transformed as follows: X (0) = Z(0) = 1, X (k) = 0, k = 1,2, . . . ,α1β1 − 1, Z(k) = 0, k = 1,2, . . . ,α2β2− 1 (32) From Eqs.(29)-(32), X (k), Y (k) and Z(k) are calculated and using the inverse transformation rule in Eq.(13), x(t),y(t) and z(t) are calculated for different values of α1 and α2. Numerical comparisons are given in Table 2-3-4.Table 2: Numeri al results of x(t) with omparison to HAM in Example 2 α = 0.5 α= 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 0.1 1.4678849 1.4678849 1.2187069 1.2187069 1.1051709 1.1051709 1.1051709 0.2 1.7411322 1.7411322 1.4000280 1.4000280 1.2214028 1.2214028 1.2214028 0.3 1.9927891 1.9927891 1.5841270 1.5841270 1.3498588 1.3498588 1.3498588 0.4 2.2392557 2.2392557 1.7769089 1.7769089 1.4918247 1.4918247 1.4918247 0.5 2.4871415 2.4871415 1.9813870 1.9813870 1.6487213 1.6487213 1.6487213 0.6 2.7401183 2.7401183 2.1997453 2.1997453 1.8221188 1.8221188 1.8221188 0.7 3.0006469 3.0006469 2.4338838 2.4338838 2.0137527 2.0137527 2.0137527 0.8 3.2706054 3.2706054 2.6856249 2.6856249 2.2255409 2.2255409 2.2255409 0.9 3.5515666 3.5515666 2.9568131 2.9568125 2.4596031 2.4596031 2.4596031 1.0 3.8450351 3.8450346 3.2493750 3.2493684 2.7182818 2.7182818 2.7182818 B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 135Table 3: Numeri al results of y(t) with omparison to HAM in Example 2 α = 0.5 α = 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 0.1 2.1546862 2.1546862 1.4852465 1.4852465 1.2214028 1.2214028 1.2214028 0.2 3.0315412 3.0315412 1.9600784 1.9600784 1.4918247 1.4918247 1.4918247 0.3 3.9712084 3.9712084 2.5094586 2.5094586 1.8221188 1.8221188 1.8221188 0.4 5.0142660 5.0142660 3.1574052 3.1574052 2.2255409 2.2255409 2.2255409 0.5 6.1858731 6.1858732 3.9258942 3.9258942 2.7182815 2.7182818 2.7182815 0.6 7.5082482 7.5082482 4.8388794 4.8388794 3.3201150 3.3201169 3.3201169 0.7 9.0038821 9.0038821 5.9237902 5.9237903 4.0551908 4.0552000 4.0552000 0.8 10.6968505 10.696866 7.2125789 7.2125809 4.9529970 4.9530324 4.9530324 0.9 12.6037326 12.603625 8.7427133 8.7427398 6.0495302 6.0496475 6.0496475 1.0 14.7830711 14.784077 10.558121 10.558395 7.3887125 7.3890561 7.3890561Table 4: Numeri al results of z(t) with omparison to HAM in Example 2 α = 0.5 α= 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 0.1 0.7235784 0.7235784 0.8282505 0.8282505 0.9048374 0.9048374 0.9048374 0.2 0.6437883 0.6437883 0.7325847 0.7325847 0.8187308 0.8187308 0.8187308 0.3 0.5920184 0.5920184 0.6603375 0.6603375 0.7408182 0.7408182 0.7408182 0.4 0.5536063 0.5536063 0.6021211 0.6021211 0.6703201 0.6703201 0.6703201 0.5 0.5231566 0.5231566 0.5536026 0.5536026 0.6065307 0.6065307 0.6065307 0.6 0.4980246 0.4980246 0.5122851 0.5122851 0.5488116 0.5488116 0.5488116 0.7 0.4767027 0.4767027 0.4765549 0.4765549 0.4965853 0.4965853 0.4965853 0.8 0.4582460 0.4582460 0.4452924 0.4452924 0.4493290 0.4493290 0.4493290 0.9 0.4420214 0.4420214 0.4176820 0.4176821 0.4065697 0.4065697 0.4065697 1.0 0.4275836 0.4275836 0.3931083 0.3931083 0.3678795 0.3678794 0.3678794 Example 3. Consider the following fractional differential- algebraic equations. x(t) + y(t) = e−t + sin(t) (33) Dα∗ x(t) + x(t)− y(t) + sin(t) = 0, 0< α ≤ 1 (34) with initial conditions as x(0) = 1, y(0) = 0 (35) For the special case when α = 1 the exact solution is x(t) = e−t , y(t) = sin(t). Eqs.(33)- (34) are transformed by using Theorems 1, 4 and 5 as follows: Y (k) = −X (k) + E(k) + S(k) (36) X (k+αβ) = Γ(1+ k/β) Γ(α+ 1+ k/β) [−X (k)+ Y (k)− S(k)] (37) B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 136 where β is the unknown value of the fractions, E(k) and S(k) are the fractional differential transform of x(t) = e−t and y(t) = sin(t) that can be evaluated using Eq.(13) as E(k) = ( (−1)k/β (k/β)! if k/β ∈ Z+ 0 if k/β /∈ Z+ (38) S(k) = ∞ ∑ i=0 (−1)i (2i+ 1)! δ(k− β(2i+ 1)) (39) From Eq.(16), initial conditions in Eq.(35) can be transformed as follows: X (0) = 1, Y (0) = 0, X (k) = Y (k) = 0, for k = 1,2, . . . ,αβ − 1 (40) From Eqs.(38)-(40), X (k) and Y (k) are calculated and using the inverse transformation rule in Eq.(13), x(t) and y(t) are calculated for different values of. Numerical comparisons are given in Table 5-6.Table 5: Numeri al results of x(t) with omparison to HAM in Example 3 α = 0.5 α= 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 0.1 0.7608910 0.7608910 0.8373931 0.8373931 0.9048374 0.9048374 0.9048374 0.2 0.6909262 0.6909262 0.7494391 0.7494391 0.8187308 0.8187308 0.8187308 0.3 0.6396502 0.6396502 0.6816129 0.6816129 0.7408182 0.7408182 0.7408182 0.4 0.5970878 0.5970877 0.6250322 0.6250322 0.6703201 0.6703201 0.6703201 0.5 0.5599926 0.5599926 0.5760122 0.5760122 0.6065307 0.6065307 0.6065307 0.6 0.5268894 0.5268894 0.5326238 0.5326238 0.5488116 0.5488116 0.5488116 0.7 0.4969640 0.4969640 0.4937128 0.4937128 0.4965853 0.4965853 0.4965853 0.8 0.4697022 0.4697024 0.4585197 0.4585198 0.4493290 0.4493290 0.4493290 0.9 0.4447448 0.4447444 0.4265076 0.4265076 0.4065697 0.4065697 0.4065697 1.0 0.4218207 0.4218206 0.3972736 0.3972738 0.3678794 0.3678795 0.3678794 Example 4. We consider the following fractional differential-algebraic equations. D α1 ∗ x(t)− t2 x(t) + y(t)− 2t = 0 (41) D α2 ∗ y(t)− 2z(t) + 2(t + 1) = 0, 0< α1,α2 ≤ 1 (42) z(t)− y(t)− 2t x(t) + t4 − t − 1= 0 (43) with initial conditions as x(0) = 0, y(0) = 0, z(0) = 1 (44) For α1 = α2 = 1 the exact solution is x(t) = t2, y(t) = t4, z(t) = 2t3 + t + 1. By using Theorems 1, 2, 4, 5 and Eq.(13), Eqs.(41)-(43) are transformed to, X (k+α1β1) = Γ(1+ k/β1) Γ(α1 + 1+ k/β1)   k ∑ l=0 δ(l − 2β1)X (k− l)− Y (k) + 2δ(k− β1)   (45) B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 137Table 6: Numeri al results of y(t) with omparison to HAM in Example 3 α = 0.5 α= 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.1 0.2437798 0.2437798 0.1672777 0.1672777 0.0998334 0.0998334 0.0998334 0.2 0.3264739 0.3264739 0.2679610 0.2679610 0.1986693 0.1986693 0.1986693 0.3 0.3966883 0.3966883 0.3547256 0.3547256 0.2955202 0.2955202 0.2955202 0.4 0.4626507 0.4626507 0.4347062 0.4347062 0.3894183 0.3894183 0.3894183 0.5 0.5259636 0.5259636 0.5099441 0.5099441 0.4794255 0.4794255 0.4794255 0.6 0.5865647 0.5865647 0.5808303 0.5808303 0.5646425 0.5646425 0.5646425 0.7 0.6438391 0.6438391 0.6470902 0.6470902 0.6442177 0.6442177 0.6442177 0.8 0.6969830 0.6969827 0.7081653 0.7081653 0.7173561 0.7173561 0.7173561 0.9 0.7451519 0.7451522 0.7633890 0.7633890 0.7833269 0.7833269 0.7833269 1.0 0.7875300 0.7875299 0.8120769 0.8120766 0.8414710 0.8414710 0.8414710 Y (k+α2β2) = Γ(1+ k/β2) Γ(α2 + 1+ k/β2) � 2Z(k)− δ(k− β2)− 2δ(k) � (46) Z(k) = Y (k) + 2 k ∑ l=0 δ(l − β)X (k− l)− 4δ(k− 4β) + δ(k− β)+ δ(k) (47) where β1 and β2 are the unknown value of the fractions and β = LC M(β1,β2).From Eq.(16), initial conditions in Eq.(44) can be transformed as follows: X (0) = 0, k = 0,1,2, . . . ,α1β1 − 1, Y (0) = 0, k = 0,1,2, . . . ,α2β2 − 1, Z(0) = 1 (48) From Eqs.(45)-(48), X (k), Y (k) and Z(k) are obtained up to and using the inverse transfor- mation rule in Eq.(13), x(t) ,y(t) and z(t) are calculated for different values of α1 and α2. Numerical comparisons are given in Table 7-8-9.Table 7: Numeri al results of x(t) with omparison to HAM in Example 4 α = 0.5 α = 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.1 0.0468839 0.0468839 0.0220868 0.0220868 0.0100000 0.0100000 0.0100000 0.2 0.1256709 0.1256709 0.0738823 0.0738823 0.0400000 0.0400000 0.0400000 0.3 0.2069285 0.2069285 0.1483883 0.1483883 0.0900000 0.0900000 0.0900000 0.4 0.2635406 0.2635406 0.2403223 0.2403223 0.1600000 0.1600000 0.1600000 0.5 0.2692381 0.2692381 0.3435494 0.3435494 0.2500000 0.2500000 0.2500000 0.6 0.2064374 0.2064374 0.4503451 0.4503451 0.3600000 0.3600000 0.3600000 0.7 0.0771395 0.0771393 0.5510811 0.5510811 0.4900000 0.4900000 0.4900000 0.8 −0.0874721 −0.0874740 0.6342822 0.6342821 0.6400000 0.6400000 0.6400000 0.9 −0.2250269 −0.2249716 0.6872107 0.6872098 0.8100000 0.8100000 0.8100000 1.0 −0.2550524 −0.2536490 0.6972563 0.6972492 1.0000000 1.0000000 1.0000000 B. İbi̧s, M. Bayram and A. Ağargün / Eur. J. Pure Appl. Math, 4 (2011), 129-141 138Table 8: Numeri al results of y(t) with omparison to HAM in Example 4 α = 0.5 α= 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.1 0.0047962 0.0047962 0.0006640 0.0006640 0.0001000 0.0001000 0.0001000 0.2 0.0446486 0.0446486 0.0079990 0.0079990 0.0016000 0.0016000 0.0016000 0.3 0.1654479 0.1654479 0.0347313 0.0347313 0.0081000 0.0081000 0.0081000 0.4 0.4099255 0.4099255 0.0988115 0.0988115 0.0256000 0.0256000 0.0256000 0.5 0.7956628 0.7956628 0.2220253 0.2220253 0.0625000 0.0625000 0.0625000 0.6 1.2918230 1.2918231 0.4277910 0.4277910 0.1296000 0.1296000 0.1296000 0.7 1.8063925 1.8063925 0.7376692 0.7376692 0.2401000 0.2401000 0.2401000 0.8 2.1992173 2.1992062 1.1662343 1.1662344 0.4096000 0.4096000 0.4096000 0.9 2.3319582 2.3316970 1.7141421 1.7141424 0.6561000 0.6561000 0.6561000 1.0 2.1509580 2.1479845 2.3596212 2.3596233 1.0000000 1.0000000 1.0000000Table 9: Numeri al results of z(t) with omparison to HAM in Example 4 α = 0.5 α= 0.75 α = 1 t xHAM xF DT M xHAM xF DT M xHAM xF DT M xExact 0.0 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 1.0000000 0.1 1.1140730 1.1140730 1.1049813 1.1049813 1.1020000 1.1020000 1.1020000 0.2 1.2933169 1.2933169 1.2359520 1.2359520 1.2160000 1.2160000 1.2160000 0.3 1.5815050 1.5815050 1.4156643 1.4156643 1.3540000 1.3540000 1.3540000 0.4 1.9951580 1.9951580 1.6654692 1.6654692 1.5280000 1.5280000 1.5280000 0.5 2.5024009 2.5024009 2.0030745 2.0030746 1.7500000 1.7500000 1.7500000 0.6 3.0099479 3.0099480 2.4386051 2.4386051 2.0320000 2.0320000 2.0320000 0.7 3.3742876 3.3742875 2.9690827 2.9690826 2.3860000 2.3860000 2.3860000 0.8 3.4496824 3.4496478 3.5714858 3.5714850 2.8240000 2.8240000 2.8240000 0.9 3.1713371 3.1706481 4.1950213 4.1950119 3.3580000 3.3580000 3.3580000 1.0 2.6477139 2.6406864 4.7541339 4.7540532 4.0000000 4.0000000 4.0000000 5. 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