J. Nig. Soc. Phys. Sci. 2 (2020) 134–140 Journal of the Nigerian Society of Physical Sciences Original Research Linear Stability Analysis of Runge-Kutta Methods for Singular Lane-Emden Equations M. O. Ogunnirana,∗, O. A. Tayoa, Y. Harunab, A. F. Adebisia aDepartment of Mathematical Sciences, Osun State University, Osogbo bDepartment of Mathematics, Saadatu Rimi College of Education Kumbotso, Kano State Abstract Runge-Kutta methods are efficient methods of computations in differential equations, the classical Runge-Kutta method of order 4 happens to be the most popular of these methods, and most times it is attached to the mind when Runge-Kutta methods are mentioned. However, there are numerous forms of them existing in lower and higher orders of the classical method. This work investigates the linear stabilities and abilities of some selected explicit members of these Runge-Kutta methods in integrating the singular Lane-Emden differential equations. The results obtained established the ability of the classical Runge-Kutta method and why is mostly used in computations. Keywords: Classical, Stability, Explicit, Lane-Emden equations, Ordinary Differential Equations Article History : Received: 13 April 2020 Received in revised form: 30 May 2020 Accepted for publication: 01 June 2020 Published: 01 August 2020 c©2020 Journal of the Nigerian Society of Physical Sciences. All rights reserved. Communicated by: T. Latunde 1. Introduction The most popular of the methods of Runge-Kutta is the clas- sical Runge-Kutta method of order 4, ’classical’ as related to the method obtained in the pre-computer era. However, many other forms of Runge-Kutta methods have been derived by nu- merous authors in the past. Existing methods of Runge-Kutta are of orders 2, 3, and orders greater than 4. Methods of orders greater than 4 are regarded as higher-order methods of Runge- Kutta. The numerical solutions of singular Initial Value Prob- lems (IVP) and Boundary Value Problems (BVP) of second- order ordinary differential equations (ODEs) have been studied in this work. Existing methods for the singular problems are ∗Corresponding author tel. no: +2347039104606 Email address: muideen.ogunniran@uniosun.edu.ng (M. O. Ogunniran ) series, analytical methods and of recent non-series numerical methods as obtained by various authors. The general form of second-order singular differential equa- tions is denoted as: y′′(x) + P(x) Q(x) y′(x) + f (x, y) = g(x, y); a ≤ x ≤ b. (1) To solve equation (1), any of the conditions stated below need to be imposed. y(a) = α, y′(a) = β (2) y(a) = α1, y ′(b) = β1 (3) Equation (1) together with (2) are called Initial Value Problems (IVPs) while equations (1) and (3) are called Boundary Value Problems (BVPs). Equation (1) is singular at Q(x) = 0, and f (x, y), g(x, y) are non- linear continuous functions. It is well known that some of these 134 Ogunniran et al. / J. Nig. Soc. Phys. Sci. 2 (2020) 134–140 135 problems have proved to be either difficult to solve or cannot be solved analytically due to the singularity as the approximate solutions lost their accuracy in the neighbourhood of the singu- lar points. This discontinuous property has raised more interest in many applied Mathematicians and Physicists in the studies of this problem. Huta [1] developed the 8-stage Runge-Kutta method of Order 6 in solving differential equation problems, Qu and Agwarwal [2] employed collocation method for solv- ing a class of singular non-linear two-point BVP. Koch, Peter & Ewa [3] evaluated the approximate solution of the singular IVP by implicit Euler method and finally used an acceleration technique known as the iterated defect correction to improve the approximations. Wazwaz [4, 5] presented series and exact solution of Lane-Emden and Emden-Fowler type of problems based on Adomian decomposition and modified Adomian de- composition methods. A Simplified Derivation and Analysis of Fourth Order Runge Kutta Method was presented by Musa, Ibrahim, & Waziri [6]. Roul [7] presented a new efficient recur- sive technique for solving singular boundary value problems arising in various physical models. Abbas Al-Shimmary [8] used the Runge-Kutta Method of order 6 to solve the initial value problem of ordinary differential equations. Roul [9] also presented a fourth-order B-spline collocation method and its er- ror analysis for Bratu-type and Lane-Emden problems. A fast- converging iterative scheme for solving a system of Lane–Emden equations arising in catalytic diffusion reactions was presented by Madduri and Roul [10]. Roul [11] presented a fast con- verging iterative approach for the solution of doubly singular BVP with derivative dependent source foundation. Ogunniran, Haruna and Adeniyi [12] developed an efficient k−derivative method for Lane-Emden equations and related stiff problems, the paper focuses on the exploration of the possibility of a class of multi-derivative methods for approximating its solution. A new basic rational approximation method was developed for solving singular initial value problems of ordinary differential equations by Ogunniran & Adeniyi [13]. Ogunniran [14] also developed a class of block multi-derivative numerical integra- tor for singular advection equations. The solution of Emden- Fowler equations was solved using the variational iteration method by Olayiwola [15]. Olayiwola and Adegoke [16] presented the approach of homotopy perturbation with Laplace transform method in solving singular initial value problems. An opti- mal sixth-order quartic B-spline collocation method was devel- oped by Roul, Thula and Goura [17] for solving Bratu-type and Lane-Emden–type problems. Roul, Madduri and Agar- wal [18] developed a fast-converging recursive approach for Lane–Emden type initial value problems arising in astrophysics. Singh, Garg, Kanwar & Ramos [19] developed an Efficient Op- timized Adaptive step-size Hybrid Block Method for Integrat- ing Differential System. This study aims at the exploration of the possibility of the classes of explicit Runge-Kutta methods in the solution of singular Lane-Emden problems of ordinary differential equations. 2. Method The general m-stage Runge-kutta method is defined by yr+1 − yr = hθ(xr, yr, h), (4) θ(x, y, h) = m∑ i=1 qiµi (5) µ1 = f (x, y) (6) µr = f (x + hpi, y + h i−1∑ s=1 bisµs); i = 2, 3, · · · , m (7) pi = i−1∑ s=1 bis, i = 2, 3, · · · , m; h = xi − xi−1 (8) It can be observed that an m-stage Runge-kutta method involves m-function evaluations per step. Each of the functions µi(x, y, h), i = 1, 2, 3, · · · , m may be interpreted as an approximation of the derivative yi(x) and the function θ(x, y, h) as a weighted mean of these approximations. There is a great deal of tedious manipulation involved in de- riving Runge-Kutta methods of the higher order. However, the forms of Runge-Kutta methods in the scope of this work shall be given in the following section. (i) 2-stage Runge-kutta method of Order 2 (RK2) yi+1 − yi = hµ2 µ1 = f (xi, yi) µ2 = f (xi + 1 2 h, yi + 1 2 hµ1) (9) (ii) 3-stage Runge-kutta method of Order 3 (RK3) yi+1 − yi = 1 6 h(µ1 + 4µ2 + µ3) µ1 = f (xi, yi) µ2 = f (xi + 1 2 h, yi + 1 2 hµ1) µ3 = f (xi + h, yi − h(µ1 − 2µ2)) (10) (iii) 4-stage Runge-kutta method of Order 4 (RK4) yi+1 − yi = 1 6 h(µ1 + 2µ2 + 2µ3 + µ4) µ1 = f (xi, yi) µ2 = f (xi + 1 2 h, yi + 1 2 hµ1) µ3 = f (xi + 1 2 h, yi + 1 2 hµ2) µ4 = f (xi + h, yi + hµ3) (11) 135 Ogunniran et al. / J. Nig. Soc. Phys. Sci. 2 (2020) 134–140 136 (iv) 6-stage kutta-Nyström method of Order 5 (RK Nyström) yi+1 − yi = 1 192 h(23µ1 + 125µ3 − 81µ5 + 125µ6) µ1 = f (xi, yi) µ2 = f (xi + 1 3 h, yi + 1 2 hµ1) µ3 = f (xi + 2 5 h, yi + 1 25 h(4µ1 + 6µ2)) µ4 = f (xi + h, yi + 1 4 h(µ1 − 12µ2 + 15µ3)) µ5 = f (xi + 2 3 h, yi + 181 h(6µ1 + 90µ2 − 50µ3 + 8µ4)) µ6 = f (xi + 4 5 h, yi + 175 h(6µ1 + 36µ2 + 10µ3 + 8µ4)) (12) (v) 8-stage Huta method of Order 6 (RK 8) yi+1 − yi = 1 840 h(4µ1 + 216µ3 + 27µ4 + 272µ5 + 27µ6 + 216µ7 + 41µ8 ) µ1 = f (xi, yi ) µ2 = f (xi + 1 9 h, yi + 1 9 hµ1 ) µ3 = f (xi + 1 6 h, yi + 1 24 h(µ1 + 3µ2 )) µ4 = f (xi + 1 3 h, yi + 1 6 h(µ1 − 3µ2 + 4µ3 )) µ5 = f (xi + 1 2 h, yi + 1 8 h(−5µ1 + 27µ2 − 24µ3 + 6µ4 )) µ6 = f (xi + 2 3 h, yi + 1 9 h(221µ1 − 9813µ2 + 867µ3 − 102µ4 + µ5 )) µ7 = f (xi + 5 6 h, yi + 1 48 h(−183µ1 + 678µ2 − 472µ3 − 66µ4 + 80µ5 + 3µ6 )) µ8 = f (xi + h, yi + 1 82 h(716µ1 − 2079µ2 + 1002µ3 + 834µ4 − 454µ5 − 9µ6 + 72µ7 )) (13) For purpose of completion and without loss of generality, special Runge-kutta methods which were developed to exhibit certain properties were also considered. (vi) 5-stage Merson’s Method of Order 4 (RK Merson) yi+1 − yi = 1 6 h(µ1 + 4µ4 + µ5) µ1 = f (xi, yi) µ2 = f (xi + 1 3 h, yi + 1 3 hµ1) µ3 = f (xi + 1 3 h, yi + 1 6 h(µ1 + µ2)) µ4 = f (xi + 1 2 h, yi + 1 8 h(µ1 + 3µ3)) µ5 = f (xi + h, yi + 1 2 h(µ1 − 3µ3 + 4µ4)) (14) (vii) 5-stage Scraton’s Method of Order 4 (RK Scraton) yi+1 − yi = h ( 17 162 µ1 + 81 170 µ3 + 32 135 µ4 + 250 1377 µ5 ) µ1 = f (xi, yi) µ2 = f (xi + 2 9 h, yi + 2 9 hµ1) µ3 = f (xi + 1 3 h, yi + 1 12 h(µ1 + 3µ2)) µ4 = f (xi + 3 4 h, yi+ 3 128 h(23µ1 − 81µ2 + 90µ3)) µ5 = f (xi + 9 10 h, yi+ 9 10000 h(−345µ1 + 2025µ2 − 1224µ3 + 544µ4)) (15) (viii) 6-stage England’s Method of Order 4 (RK England) yi+1 − yi = 1 6 h(µ1 + 4µ3 + µ4) µ1 = f (xi, yi) µ2 = f (xi + 1 2 h, yi + 1 2 hµ1) µ3 = f (xi + 1 2 h, yi + 1 4 h(µ1 + µ2)) µ4 = f (xi + h, yi − h(µ2 − 2µ3)) µ5 = f (xi + 2 3 h, yi+ 1 27 h(7µ1 + 10µ2 + µ4)) µ6 = f (xi + 1 5 h, yi+ 1 625 h(28µ1 − 125µ2 + 546µ3 + 54µ4 − 378µ5)) (16) Figure 1. Stability Region for Runge-kutta Method of Order 2 2.1. Linear Stability This is a behaviourial property related to h > 0. As in most literature, the linear stability will be analyzed using the Dalquist’s test y′(t) = γy(t), <(γ) < 0. (17) Applying methods (9)-(16) on (17), we have obtained a recur- rence equation yi = M(z)yi−1 (18) where M(z = hγ) for each of the method is given in Table 1 below The contour for regions of absolute stability as obtained from their characteristics equations are given in Figure 1 - 8. 3. Numerical Experiment This section contains the numerical example considered and their results presented in tables of absolute errors. Example 1: Variable Coefficient Non-homogeneous Singular IVP [3] y′′(x) = −2x y ′(x) − n2cos(nx) − 2 x nsin(nx); y(0) = 2, y ′(0) = 0 Theoretical Solution : y(x) = 1 + cos(nx)  (19) * Absolute Error=|E xact solution − Numerical solution|, Nu- merical solution is obtained using the Runge-kutta methods. Example 2: Variable Coefficient Homogeneous Singular Initial BVP [6] (x2y′)′ = β(xy′ + y(α + β− 1))xα+β−2, 0 ≤ x ≤ 1. y(0) = 1, y(1) = ex p(1) Theoretical Solution = exp(x4) (20) 136 Ogunniran et al. / J. Nig. Soc. Phys. Sci. 2 (2020) 134–140 137 Table 1. Table of Characteristics Equations for Runge-kutta Methods Method M(z), z = hλ (9) 14 z 2 + 12 z + 1 (10) 16 z 3 + 12 z 2 + z + 1 (11) 124 z 4 + 16 z 3 + 12 z 2 + z + 1 (12) 1120 z 5 + 124 z 4 + 16 z 3 + 12 z 2 + z + 1 (13) z 8 483840 + z7 4480 + z6 720 − 179 z5 4032 − 3049 z4 3360 − 3119 z3 420 − 3119 z2 140 + 803 z 840 + 1 (14) 136 z 4 + 16 z 3 + 12 z 2 + z + 1 (15) 196 z 5 + 124 z 4 + 16 z 3 + 12 z 2 + z + 1 (16) 124 z 4 + 16 z 3 + 12 z 2 + z + 112 Table 2. Table of Absolute Errors for Example 1, n = 3 at different h h x y(x) RK2 RK3 RK4 RK Nyström RK Merson RK Scraton RK England RK8 10−1 0.2 9.1982 × 10−2 9.0000 × 100 5.0392 × 10−2 4.5167 × 10−2 1.3355 × 10−1 7.61289 × 100 5.0392 × 10−2 1.1722 × 100 0.5 7.7896 × 10−2 9.0000 × 100 2.0474 × 10−2 7.5533 × 10−2 1.6385 × 10−1 8.3700 × 100 2.04738 × 10−2 1.2308 × 100 0.7 8.1030 × 10−2 9.0000 × 100 1.4680 × 10−2 8.1382 × 10−2 1.6970 × 10−1 7.4117 × 100 1.4680 × 10−2 1.2624 × 100 10−2 0.04 7.0148 × 10−4 9.0000 × 100 2.5148 × 10−4 7.0046 × 10−4 1.5808 × 10−3 9.7960 × 10−1 2.5148 × 10−4 1.2152 × 10−2 0.4 5.7493 × 10−4 9.0000 × 100 2.5188 × 10−5 9.2689 × 10−4 1.8072 × 10−3 2.7924 × 100 2.5188 × 10−5 3.9599 × 10−2 0.9 7.5147 × 10−4 9.0000 × 10+1 1.1203 × 10−5 9.4089 × 10−4 1.8212 × 10−3 1.200 × 10−2 1.1203 × 10−5 9.5724 × 10−2 10−3 0.09 4.7178 × 10−6 9.0000 × 100 1.1179 × 10−7 9.4074 × 10−6 1.8210 × 10−5 8.2736 × 10−1 1.1179 × 10−7 1.6996 × 10−3 0.19 4.8424 × 10−6 9.0000 × 10+1 5.2955 × 10−8 9.4662 × 10−6 1.8269 × 10−5 1.5242 × 100 5.2955 × 10−8 7.0497 × 10−3 0.69 6.7846 × 10−6 9.0000 × 10+1 1.4584 × 10−8 9.5046 × 10−6 1.8307 × 10−5 1.2185 × 100 1.4584 × 10−8 6.5798 × 10−2 Cmpt Time (s) 0.0025 0.0022 0.0035 0.0059 0.0039 0.0077 0.0065 0.021 Table 3. Table of Absolute Errors for Example 2 Using α = 2, β = 4 h x y(x) RK2 RK3 RK4 RK Nyström RK Merson RK Scraton RK England RK8 1 10 0.2 1.5913 × 10−3 1.5954 × 10−3 1.5745 × 10−3 1.5610 × 10−3 1.5706 × 10−3 7.0036 × 10−4 1.5745 × 10−3 1.5705 × 10−3 0.5 5.8226 × 10−2 5.8697 × 10−2 5.7050 × 10−2 5.7009 × 10−2 5.7014 × 10−2 2.5489 × 10−2 5.7050 × 10−2 5.7175 × 10−2 0.8 3.8263 × 10−1 3.8559 × 10−1 3.7177 × 10−1 3.7160 × 10−1 3.7166 × 10−1 5.7962 × 10−1 3.7177 × 10−1 3.7544 × 10−1 1 16 0.125 2.4357 × 10−4 2.4382 × 10−4 2.4258 × 10−4 2.4231 × 10−4 2.4234 × 10−4 1.5826 × 10−4 2.4258 × 10−4 2.4233 × 10−4 0.5 5.7534 × 10−2 5.7757 × 10−2 5.7026 × 10−2 5.7019 × 10−2 5.7020 × 10−2 2.5563 × 10−2 5.7026 × 10−2 5.7237 × 10−2 0.75 2.6863 × 10−1 2.8731 × 10−1 2.8304 × 10−1 2.8302 × 10−1 2.8303 × 10−1 3.7761 × 10−1 2.8304 × 10−1 2.8600 × 10−1 1 32 0.25 3.8056 × 10−3 3.8090 × 10−3 3.7977 × 10−3 3.7976 × 10−3 3.7976 × 10−3 1.1239 × 10−3 3.7977 × 10−3 3.8001 × 10−3 0.5625 9.0304 × 10−2 9.0405 × 10−2 9.0077 × 10−2 9.0076 × 10−2 9.0077 × 10−2 5.8501 × 10−2 9.0077 × 10−2 9.0639 × 10−2 0.875 5.5592 × 10−1 5.5618 × 10−1 5.5376 × 10−1 5.5538 × 10−1 5.5376 × 10−1 1.0939 × 100 5.5376 × 10−1 5.6323 × 10−1 Cmpt Time (s) 0.0023 0.0026 0.0042 0.0055 0.0033 0.0061 0.0055 0.011 137 Ogunniran et al. / J. Nig. Soc. Phys. Sci. 2 (2020) 134–140 138 Figure 2. Stability Region for Runge-kutta Method of Order 3 Figure 3. Stability Region for Runge-kutta Method of Order 4 Figure 4. Stability Region for Kutta-Nyström Method Example 3: Variable Coefficient Non-linear Homogeneous Sin- gular IVP [3] y′′(x) = −2x y ′(x) − y5(x); x ∈ [0, 1] y(0) = 1, y′(0) = 0 Theoretical Solution : y(x) = 1√ 1+ x 2 3 (21) Figure 5. Stability Region for Runge-kutta Method of Order 6 Figure 6. Stability Region for Merson’s Method Figure 7. Stability Region for Scraton’s Method Example 4: Van der Pol Singular Problem [11] y′′ = y ′(1−y′2 )−y µ ; y(0) = 2, y′(0) = −23 + 10 81 µ− 292 2187 µ 2 − 1814 19683 µ 3; µ = 10−1. (22) The methods considered in this work were used to approximate the problem over the interval [0, 0.55139] for h = 10−3. 138 Ogunniran et al. / J. Nig. Soc. Phys. Sci. 2 (2020) 134–140 139 Table 4. Table of Absolute Errors for Example 3 Using different h h x y(x) RK2 RK3 RK4 RK Nyström RK Merson RK Scraton RK England RK8 1 7 0.2857 2.4565 × 10−2 9.7182 × 10+6 2.7524 × 10−2 3.4496 × 10−2 4.1169 × 10−2 3.5739 × 10−2 2.7525 × 10−2 1.1722 × 10−1 0.5714 2.8265 × 10−2 9.7182 × 10+6 3.1850 × 10−2 3.8832 × 10−2 4.54985 × 10−2 3.9917 × 10−1 3.1851 × 10−2 1.2281 × 10−1 0.8571 1.0144 × 10−2 9.7182 × 10+6 1.4411 × 10−2 2.1093 × 10−2 2.7780 × 10−2 4.0945 × 10−1 1.4112 × 10−2 1.0723 × 10−1 1 14 0.2857 2.9836 × 10−2 1.2148 × 10+6 3.0700 × 10−2 3.2486 × 10−2 3.4150 × 10−2 2.1129 × 10−1 3.0701 × 10−2 5.4061 × 10−2 0.4286 3.4167 × 10−2 1.2148 × 10+6 3.5075 × 10−2 3.0686 × 10−2 3.8524 × 10−2 2.3129 × 10−1 3.5075 × 10−2 5.9065 × 10−2 0.6429 2.8969 × 10−2 1.2148 × 10+6 2.9944 × 10−2 3.1729 × 10−2 3.3393 × 10−2 2.4973 × 10−1 2.9944 × 10−2 5.5316 × 10−2 1 21 0.4286 3.4837 × 10−2 3.5993 × 10+5 3.5246 × 10−2 3.6042 × 10−2 3.6782 × 10−2 1.7714 × 10−1 3.5246 × 10−2 4.6596 × 10−2 0.6667 2.8266 × 10−2 3.5999 × 10+5 2.8707 × 10−2 2.9504 × 10−2 3.0243 × 10−2 1.9637 × 10−1 2.8707 × 10−2 4.1652 × 10−2 0.9048 9.3712 × 10−3 3.5993 × 10+5 9.8446 × 10−3 1.0641 × 10−2 1.1138 × 10−2 1.9780 × 10−1 9.8446 × 10−3 2.4823 × 10−2 Cmpt Time (s) 0.0025 0.0021 0.0035 0.0059 0.0045 0.0077 0.0051 0.021 Figure 8. Stability Region for England’s Method Table 5. Numerical Results for Example 4 at x = 0.55139 h Method y(x) Cmpt. Time (s) RK2 0.625821430245524 0.0025 RK3 0.625821606669667 0.0019 RK4 0.625821602543592 0.0065 10−3 RK Nyström 0.625821602551168 0.018 RK Merson 0.625821602551009 0.0028 RK Scarton -0.031597285014076 0.025 RK England 0.625821602543570 0.0021 RK 8 0.642280546551478 0.063 4. Discussion of Results and Conclusion It is worthy to note that numerical methods were programmed via MATLAB 9.2 version on a personal computer with the fol- lowing specifications: • System name- HP Pavilion x360 Convertible • Processor- Intel(R) Core(TM) i3-7100U CPU @ 2.40GHz • Installed memory (RAM)- 8.00GB • System Type- 64-bits Operating System, x64-based pro- cessor • Operating system- Windows 10 Cmpt time is the computer computation time measured in seconds(s). This paper presents the performances of different orders of Runge-Kutta methods in the integration of singular Lane-Emden equations. From Tables 2-4, It could be observed that the Runge-Kutta method of order 4 performs the best in terms of accuracy. The methods of order 3, Scraton’s, and order 8 were found to have failed in the solution of singular problems in ordinary differential equations. The England’s method per- forms more satisfactorily as it shows some competitive strength against the order 4 method. It could be concluded that the Runge-Kutta method of order 4 outperforms all other methods under consideration and this property makes it the most stable and accurate of the Runge-Kutta methods. Acknowledgments The authors thank the referees and editor for their valuable comments and suggestions. References [1] A. Huta, “Contribution à la formule de sixieme ordre dans la methode de Runge-kutta-Nyström”, Acta Fac Rerum Natu Univ. Comenian Math. 2 (1957) 21. [2] R. Qu & R. P. Agarwal, “A collocation method for solving a class of sin- gular non-linear two-point boundary value problems”, Journal Computer Application Mathematics 83 (1997) 147. [3] O. Koch, K. Peter & B. W. Ewa, “The Implicit Euler method for the nu- merical solution of singular initial value problems”, Applied Numerical Mathematics 34 (2000) 231 [4] A. M. Wazwaz, “A new algorithm for solving differential equation of Lane-Emden type”, Applied Mathematics and Computation 118 (2001) 287. [5] A. M. Wazwaz, “Adomian decomposition method for a reliable treatment of the Emden-Fowler equation”, Applied Mathematics and Computation 61 (2005) 543. [6] H. Musa, S. Ibrahim & M. Y. Waziri, “A Simplified Derivation and Anal- ysis of Fourth Order Runge Kutta Method”, International Journal of Com- puter Applications 9 (2010) 51. [7] P. Roul, “A new efficient recursive technique for solving singular bound- ary value problems arising in various physical models”, The European Physical Journal Plus 131 (2016), doi.org/10.1140/epjp/i2016-16105-8. 139 Ogunniran et al. / J. Nig. Soc. Phys. Sci. 2 (2020) 134–140 140 [8] A. Abbas Al-Shimmary, “Solving Initial Value Problem Using Runge- kutta 6th Order Method”, ARPN Journal of Engineering and Applied Sci- ences 12 (2017) 3953. [9] P. Roul & K. Thula, “A fourth order B-spline collocation method and its error analysis for Bratu-type and Lane-Emden problems”, International Journal of Computer Mathematics 96 (2017) 85. [10] H. Madduri, & P. Roul, “A fast-converging iterative scheme for solving a system of Lane–Emden equations arising in catalytic diffusion reactions”, Journal of Mathematical Chemistry 57 (2018) 570. [11] P. Roul, “Doubly singular boundary value problems with derivative de- pendent source function: A fast converging iterative approach”, Journal of Math Methods Application Science 42 (2018) 354. [12] M. O. Ogunniran, Y. Haruna, & R. B. Adeniyi, “Efficient k-derivative Methods for Lane-Emden Equations and Related Stiff Problems”, Nige- rian Journal of Mathematics and Applications 28 (2019) 1. [13] M. O. Ogunniran & R. B. Adeniyi, “New Basic Rational Approximation Method for Solving Singular Initial Value Problems of Ordinary Differen- tial Equations”, ABACUS (Mathematics Science Series) 46 (2019) 119. [14] M. O. Ogunniran, “A Class of Block Multi-Derivative Numerical Integra- tor for Singular Advection Equations”, Journal of the Nigerian Society of Physical Sciences 1 (2019) 62. [15] M. O. Olayiwola, “Solutions of Emden-Fowler Type Equations by Varia- tional Iteration Method”, Cankaya University Journal of Science and En- gineering 16 (2019) 1. [16] M. O. Olayiwola & A. Adegoke, “Homotopy Perturbation with Laplace Transforms Method for Solving Singular Initial Value Problems” Nige- rian Journal of Mathematics and Applications 28 (2019) 65. [17] P. Roul, K. Thula & V. Goura, “An optimal sixth-order quartic B-spline collocation method for solving Bratu-type and Lane-Emden–type prob- lems”, Journal of Computational and Applied Mathematics 359 (2019) 182. [18] P. Roul, H. Madduri & R. Agarwal, “A fast-converging recursive approach for Lane-Emden type initial value problems arising in astrophysics”, Jour- nal of Math Methods Application Science 42 (2019) 2613. [19] G. Singh, A. Garg, V. Kanwar & H. Ramos, “An Efficient Optimized Adaptive Step-size Hybrid Block Method for Integrating Differential Sys- tems”, Applied Mathematics and Computation, 362 (2019) 124567. [20] J. D. Lambert, Computational Methods in Ordinary Differential Equa- tions, John Wiley and Sons, New York, 1991. 140