375 This work is licensed under a Creative Commons Attribution 4.0 International License IHJPAS. 37 (1) 2024 Ibn Al-Haitham Journal for Pure and Applied Sciences Journal homepage: jih.uobaghdad.edu.iq PISSN: 1609-4042, EISSN: 2521-3407 1Omar Mohammed Saleh 2 Firas Adel Fawzi 3Kasim Abbas Hussain* 4Nizam G. Ghawadri 1,2Department of Mathematics, Faculty of Computer Science and Mathematics, University of Tikrit, Tikrit, Iraq. 3Department of Mathematics, College of Science, Mustansiriyah University, Baghdad, Iraq. 4Doctor of Mathematics, Ministry of Education, Jenin, Palestine. *Corresponding Author. kasimabbas@uomustansiriyah.edu.iq Abstract EDIRKTO is an Implicit Type Runge-Kutta Method of Diagonally Embedded pairs, is a novel approach presented in the paper that may be used to solve 4th-order ordinary differential equations of the form ๐‘ž(4)(๐‘ก) = ๐‘“(๐‘ก, ๐‘ž(๐‘ก), ๐‘žโ€ฒ(๐‘ก)). There are two pairs of EDIRKTO, with three stages each: EDIRKTO4(3) and EDIRKTO5(4). The derivation techniques of the method indicate that the higher-order pair is more accurate, while the lower-order pair provides superior error estimates. Next, using these pairs as a basis, we developed variable step codes and applied them to a series of 4๐‘กโ„Ž-order ODE problems. The numerical outcomes demonstrated how much more effective their approach is in reducing the quantity of function evaluations needed to resolve fourth-order ODE issues. Keywords: Fourth-order ODEs; Runge-Kutta methods; diagonally implicit technique; embedded method. 1. Introduction Differential equations (DEs) are important tools in mathematical modeling, particularly in explaining physical phenomena like heat and fluid movement, object motion, and nuclear reactions. ODEs of different orders are used in various applied research fields such as mechanics, electrical and control engineering, fluid dynamics, ship dynamics, neural networks, and beam theory [1-3]. Numerical and approximated methods have been developed to solve specific types of DEs. Received 17 February 2023, Received 15 April 2023, Accepted 10 May 2023, Published 20 January 2024 Derivation of Embedded Diagonally Implicit Methods for Directly Solving Fourth-order ODEs doi.org/ 10.30526/37.1.3288 https://creativecommons.org/licenses/by/4.0/ https://jih.uobaghdad.edu.iq/index.php/j/index#1609-4042 https://jih.uobaghdad.edu.iq/index.php/j/index#2521-3407 mailto:kasimabbas@uomustansiriyah.edu.iq https://orcid.org/0009-0003-6837-6231 mailto:Oommaarr7ag7@gmail.com https://orcid.org/0000-0003-0939-7940 mailto:firasadil01@tu.edu.iq https://orcid.org/0000-0001-9389-3861 mailto:kasimabbas@uomustansiriyah.edu.iq https://orcid.org/0000-0002-4335-1789 mailto:nizamghawadri@gmail.com IHJPAS. 37 (1) 2024 376 In this study, we discuss a class of quasi-linear, fourth-order (ODEs) and their numerical integration in the following form: ๐‘ž(4)(๐‘ก) = ๐‘“(๐‘ก, ๐‘ž(๐‘ก), ๐‘žโ€ฒ(๐‘ก)), ๐‘ก โ‰ฅ ๐‘ก0, (1) with initial conditions ๐œŽ๐‘–(๐œ) = ๐œ๐‘–, ๐‘– = 0, 1, โ€ฆ , 3. Where ๐‘“ โˆถ โ„› ร— โ„›๐‘ โŸถ โ„›๐‘ , ๐œŽ(๐œ) = [๐œŽ1(๐œ), ๐œŽ2(๐œ), โ€ฆ , ๐œŽ๐‘(๐œ)] , ๐‘ก(๐œ, ๐œŽ) = [๐‘ก1(๐œ, ๐œŽ), ๐‘ก2(๐œ, ๐œŽ), โ€ฆ , ๐‘ก๐‘(๐œ, ๐œŽ)], and ๐œ๐‘– = [๐œ1 i , ๐œ2 i , โ€ฆ , ๐œN i ], where i = 0,1,2, โ€ฆ ,4. Previously, researchers transformed Equation (1) into a system of first-order ODEs with four additional dimensions to solve it. However, it would be more efficient if numerical methods could be used to solve the problem accurately and quickly. In [4-12] contain such works. Multistep strategies for solving ODEs require initial values. However, according to several researchers (see [1, 13, 14]) this technique has a drawback as it consumes a lot of computing time and human effort. Consequently, several researchers have turned their attention to direct integration methods for solving higher-order ODEs, as these methods have demonstrated features of accuracy and speed [16-30]. Nevertheless, all of the methods mentioned above are above are multistep. The primary objective of this paper is to introduce a new technique named EDIRKTO, which is a one-step implicit Runge-Kutta method created to directly solve general 4๐‘กโ„Ž-order differential equations. The method involves deriving diagonally embedded implicit Runge-Kutta methods for the direct integration of specific 4๐‘กโ„Ž-order differential equations. To address the IVPs problem in (1), the special version of the EDIRKTO method with ๐‘š stages is as follows: ๐‘ž๐‘›+1 = ๐‘ž๐‘› + โ„Ž ๐‘ž๐‘› โ€ฒ + โ„Ž2 2 ๐‘ž๐‘› โ€ฒโ€ฒ + โ„Ž3 6 ๐‘ž๐‘› โ€ฒโ€ฒโ€ฒ + โ„Ž4 โˆ‘ ๐‘๐‘–๐‘“(๐‘ก๐‘› + ๐‘๐‘—โ„Ž๐‘  ๐‘–=1 , ๐‘„๐‘–, ๐‘„๐‘– โ€ฒ), (2) ๐‘ž๐‘›+1 โ€ฒ = ๐‘ž๐‘› โ€ฒ + โ„Ž ๐‘ž๐‘› โ€ฒโ€ฒ + โ„Ž2 2 ๐‘ž๐‘› โ€ฒโ€ฒโ€ฒ + โ„Ž3 โˆ‘ ๐‘๐‘– โ€ฒ ๐‘“(๐‘ก๐‘› + ๐‘๐‘—โ„Ž, ๐‘„๐‘–, ๐‘„๐‘– โ€ฒ),๐‘  ๐‘–=1 (3) ๐‘ž๐‘›+1 โ€ฒโ€ฒ = ๐‘ž๐‘› โ€ฒโ€ฒ + โ„Ž ๐‘ž๐‘› โ€ฒโ€ฒโ€ฒ + โ„Ž2 โˆ‘ ๐‘โ€ฒ๐‘– โ€ฒ ๐‘“(๐‘ก๐‘› + ๐‘๐‘—โ„Ž, ๐‘„๐‘–, ๐‘„๐‘– โ€ฒ),๐‘  ๐‘–=1 (4) ๐‘ž๐‘›+1 โ€ฒโ€ฒโ€ฒ = ๐‘ž๐‘› โ€ฒโ€ฒโ€ฒ + โ„Ž โˆ‘ ๐‘โ€ฒโ€ฒ๐‘– โ€ฒ ๐‘“(๐‘ก๐‘› + ๐‘๐‘—โ„Ž, ๐‘„๐‘–, ๐‘„๐‘– โ€ฒ),๐‘  ๐‘–=1 (5) ๐‘„๐‘— = ๐‘ž๐‘› + โ„Ž ๐‘๐‘–๐‘ž๐‘› โ€ฒ + โ„Ž2 2 ๐‘๐‘– 2๐‘ž๐‘› โ€ฒโ€ฒ + โ„Ž3 6 ๐‘๐‘– 3๐‘ž๐‘› โ€ฒโ€ฒโ€ฒ + โ„Ž4 โˆ‘ ๐‘Ž๐‘–๐‘—๐‘“(๐‘ก๐‘› + ๐‘๐‘—โ„Ž, ๐‘„๐‘—, ๐‘„๐‘— โ€ฒ)๐‘  ๐‘—=1 , (6) ๐‘„๐‘— โ€ฒ = ๐‘ž๐‘› โ€ฒ + โ„Ž ๐‘๐‘–๐‘ž๐‘› โ€ฒโ€ฒ + โ„Ž2 2 ๐‘๐‘– 2๐‘ž๐‘› โ€ฒโ€ฒโ€ฒ + โ„Ž3 โˆ‘ ๏ฟฝฬ…๏ฟฝ๐‘–๐‘—๐‘“(๐‘ก๐‘› + ๐‘๐‘—โ„Ž, ๐‘„๐‘— , ๐‘„๐‘— โ€ฒ)๐‘  ๐‘—=1 . (7) The coefficients ๐‘๐‘–, ๐‘๐‘– โ€ฒ, ๐‘๐‘– โ€ฒโ€ฒ, ๐‘๐‘– โ€ฒโ€ฒโ€ฒ, ๐‘Ž๐‘–,๐‘— , ๏ฟฝฬ…๏ฟฝ๐‘–๐‘— and ๐‘๐‘– of diagonal implicit RK type (EDIRKTO) methods are real numbers. The method is diagonally implicit when ๐‘Ž๐‘–,๐‘— โ‰  0 for ๐‘– โ‰ค ๐‘—. Using the Butcher tableau, the EDIRKT approach is illustrated. See Table 1. IHJPAS. 37 (1) 2024 377 Table 1. The Butcher tableau EDIRKTO method 3. Order Conditions of the EDIRKTO Method According to Ghawadri [15], the algebraic order conditions for the EDIRKTO formula up to order seven are as follows: order 1: โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ = 1, order 2: โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘– = 1 2 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ = 1 2 , order 3: โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘– 2 = 1 3 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ๐‘๐‘– = 1 6 , โˆ‘ ๐‘๐‘– โ€ฒ = 1 6 , order 4: โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘– 3 = 1 4 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘Ž๐‘–๐‘—ฬ…ฬ… ฬ…ฬ… = 1 24 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ๐‘๐‘– 2 = 1 12 , โˆ‘ ๐‘๐‘– โ€ฒ๐‘๐‘– = 1 24 , โˆ‘ ๐‘๐‘– = 1 24 , order 5: โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘– 4 = 1 5 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘Ž๐‘–๐‘— = 1 120 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๏ฟฝฬ…๏ฟฝ๐‘–๐‘—๐‘๐‘— = 1 120 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘–๏ฟฝฬ…๏ฟฝ๐‘–๐‘— = 1 30 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ๐‘๐‘– 3 = 1 20 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ๐‘Ž๐‘–๐‘— = 1 120 , โˆ‘ ๐‘๐‘– โ€ฒ๐‘๐‘– 2 = 1 60 , โˆ‘ ๐‘๐‘–๐‘๐‘– = 1 120 , order 6: โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘– 5 = 1 6 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘Ž๐‘–๐‘—๐‘๐‘— = 1 720 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๏ฟฝฬ…๏ฟฝ๐‘–๐‘—๐‘๐‘– 2 = 1 360 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘– 2๏ฟฝฬ…๏ฟฝ๐‘–๐‘— = 1 36 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘–๏ฟฝฬ…๏ฟฝ๐‘–๐‘—๐‘๐‘— = 1 144 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒโ€ฒ๐‘๐‘–๐‘Ž๐‘–๐‘— = 1 144 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ๐‘๐‘– 4 = 1 30 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ๏ฟฝฬ…๏ฟฝ๐‘–๐‘—๐‘๐‘— = 1 720 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ๐‘๐‘–๏ฟฝฬ…๏ฟฝ๐‘–๐‘— = 1 180 , โˆ‘ ๐‘๐‘– โ€ฒโ€ฒ๏ฟฝฬ…๏ฟฝ๐‘–๐‘— = 1 720 , โˆ‘ ๐‘๐‘– โ€ฒ๐‘๐‘– 3 = 1 120 , โˆ‘ ๐‘๐‘–๐‘๐‘– 2 = 1 360 , โˆ‘ ๐‘๐‘– โ€ฒ๏ฟฝฬ…๏ฟฝ๐‘–๐‘— = 1 720 . 4. Derivation Embedded EDIRKTO Methods To solve Equation (1) numerically, the general form of the EDIRKTO technique with ๐‘š-stage is given. The embedded pair RK method, a current research area that is constantly enhancing existing programs, is then developed. The derivation of ๐‘(๐‘ž) pairs of implicit EDIRKTO approaches is used to provide minimum error estimation for step size codes. Both the order ๐‘ method (๐ถ, ๐ด, ๐‘, ๐‘โ€ฒ๐‘‡ , ๐‘โ€ฒโ€ฒ๐‘‡ , ๐‘โ€ฒโ€ฒโ€ฒ๐‘‡) and the order ๐‘ž method (๐ถ, ๏ฟฝฬ…๏ฟฝ, ๐‘1 ๐‘‡ , ๐‘โ€ฒ2 ๐‘‡ , ๐‘โ€ฒโ€ฒ3 ๐‘‡ , ๐‘โ€ฒโ€ฒโ€ฒ4 ๐‘‡) constitute the foundation for them. The embedded pair can be launched in Butcher Tabular as follows: ๐‘1 ๐‘Ž11 ๐‘Ž12 โ€ฆ ๐‘Ž1๐‘  ๏ฟฝฬ…๏ฟฝ11 ๏ฟฝฬ…๏ฟฝ12 โ€ฆ ๏ฟฝฬ…๏ฟฝ1๐‘  ๐‘2 ๐‘Ž21 ๐‘Ž22 โ€ฆ ๐‘Ž2๐‘  ๏ฟฝฬ…๏ฟฝ21 ๏ฟฝฬ…๏ฟฝ22 โ€ฆ ๏ฟฝฬ…๏ฟฝ2๐‘  ๐‘3 ๐‘Ž31 ๐‘Ž32 โ€ฆ ๐‘Ž3๐‘  ๏ฟฝฬ…๏ฟฝ31 ๏ฟฝฬ…๏ฟฝ32 โ€ฆ ๏ฟฝฬ…๏ฟฝ3๐‘  โ‹ฎ โ‹ฎ โ‹ฎ โ‹ฎ โ‹ฎ โ‹ฎ โ‹ฎ โ‹ฎ โ‹ฎ ๐‘๐‘  ๐‘Ž๐‘ 1 ๐‘Ž๐‘ 2 โ€ฆ ๐‘Ž๐‘ ๐‘  ๏ฟฝฬ…๏ฟฝ๐‘ 1 ๏ฟฝฬ…๏ฟฝ๐‘ 2 โ€ฆ ๏ฟฝฬ…๏ฟฝ๐‘ ๐‘  ๐‘1 ๐‘2 โ€ฆ ๐‘๐‘  ๐‘1 โ€ฒ ๐‘2 โ€ฒ โ€ฆ ๐‘๐‘  โ€ฒ ๐‘1 โ€ฒโ€ฒ ๐‘โ€ฒ2 โ€ฒ โ€ฆ ๐‘๐‘  โ€ฒโ€ฒ ๐‘1 โ€ฒโ€ฒโ€ฒ ๐‘โ€ฒโ€ฒ2 โ€ฒ โ€ฆ ๐‘๐‘  โ€ฒโ€ฒโ€ฒ IHJPAS. 37 (1) 2024 378 Table 2. The Embedded Pair EDIRKTO Method ๐ถ ๐ด ๏ฟฝฬ…๏ฟฝ ๐‘๐‘‡ ๐‘โ€ฒ๐‘‡ ๐‘โ€ฒโ€ฒ๐‘‡ ๐‘โ€ฒโ€ฒโ€ฒ๐‘‡ ๐‘1 ๐‘‡ ๐‘2 โ€ฒ๐‘‡ ๐‘3 โ€ฒโ€ฒ๐‘‡ ๐‘4 โ€ฒโ€ฒโ€ฒ๐‘‡ The main idea is to obtain single cost error estimation for usage in step size approach values before generating the embedded pair of implicit EDIRKTO approaches. The methods are illustrated by increasing the significant pairs and local error estimates using the values step size โ„Ž, as follows [8], โ„Ž๐‘›+1 = 0.9โ„Ž๐‘› ( ๐‘‡๐‘œ๐‘™ ๐ฟ๐‘‡๐ธ ) 1 ๐‘ž+1 , (8) Where ๐‘‡๐‘œ๐‘™ refers to the required level of accuracy, and local truncation error (LTE) is performed at each stage. Therefore, the step will be admitted if ๐ฟ๐‘‡๐ธ โ‰ค ๐‘‡๐‘œ๐‘™, uses the local extrapolation method, which indicates employing more precise calculations to boost the integration and โ„Ž can be improved by using Equation (8). If ๐ฟ๐‘‡๐ธ > ๐‘‡๐‘œ๐‘™, the step will be denied and the step size โ„Ž will be cut in half. Fourth-order ODEs can be solved using the EDIRKTO technique, an embedded RK- type method. The first pair has orders 3 and 4, whereas the second pair contains orders 4 and 5. These methods were built utilizing sections, which confirm that the lower-order methods produced the most accurate error estimates while the higher-order methods were extremely accurate. Therefore, doubling the step size โ„Ž has an impact on getting the correct results. The two derivations for the embedded EDIRKTO4(3) and embedded EDIRKTO5(4) methods used in this work are shown in Tables 3 and 4. The ๐ด and ๐ถ values in EDIRKTO4(3) are calculated from the 4๐‘กโ„Ž-order solution and then obtained from the three-stage embedded 3๐‘Ÿ๐‘‘-order equation. The simultaneous solution of equations, followed by the solution of ๐‘1 ๐‘‡ , ๐‘โ€ฒ2 ๐‘‡ , and ๐‘โ€ฒโ€ฒ3 ๐‘‡ while ๐‘โ€ฒโ€ฒโ€ฒ4 ๐‘‡ has the same values as the 4๐‘กโ„Ž-order. The outcomes are as follows: ๐‘1 ๐‘‡ = 1 6 โˆ’ ๐‘โ€ฒ 2 ๐‘‡ โˆ’ ๐‘โ€ฒ 3 ๐‘‡ , ๐‘โ€ฒ 2 ๐‘‡ = ๐‘โ€ฒ 2 ๐‘‡ , ๐‘โ€ฒ 3 ๐‘‡ = ๐‘โ€ฒ 3 ๐‘‡ , ๐‘โ€ฒโ€ฒโ€ฒ 1 ๐‘‡ = 0, ๐‘โ€ฒโ€ฒโ€ฒ 2 ๐‘‡ = 1 2 , ๐‘โ€ฒโ€ฒโ€ฒ 3 ๐‘‡ = 1 2 , ๐‘โ€ฒโ€ฒ 1 ๐‘‡ = โˆ’ 1 2 + ๐‘โ€ฒโ€ฒ 3 ๐‘‡ + ๐‘โ€ฒโ€ฒ 3 ๐‘‡ โˆš3 + 1 3 โˆš3 , ๐‘โ€ฒโ€ฒ 2 ๐‘‡ = โˆ’2๐‘โ€ฒโ€ฒ 3 ๐‘‡ + ๐‘โ€ฒโ€ฒ 3 ๐‘‡ โˆš3 โˆ’ โˆš3 3 + 1, ๐‘โ€ฒโ€ฒ 3 ๐‘‡ = ๐‘โ€ฒโ€ฒ 3 ๐‘‡ . According to [12], using the minimized command in Maple to minimize the LTE, we can calculate the free parameters as follows: ๐‘โ€ฒ2 ๐‘‡= -0.0142606637044632, ๐‘โ€ฒ3 ๐‘‡=0.644727870311524 and ๐‘โ€ฒโ€ฒ3 ๐‘‡= 0.105662412164532. If the value is optimized in fractional form, then ๐‘โ€ฒ2 ๐‘‡ = โˆ’ 1 100 , ๐‘โ€ฒ 3 ๐‘‡ = 6 10 , and ๐‘โ€ฒโ€ฒ3 ๐‘‡ = 1 10 are chosen. IHJPAS. 37 (1) 2024 379 Table 3. The Embedded Pair EDIRKTO4 (3) Method. 1 โˆ’ 1 4 โˆ’ 2 1000 1 2 โˆ’ โˆš3 6 3 10 โˆ’ 1 4 0 0 โˆ’ 2 1000 1 2 + โˆš3 6 3 10 3 10 โˆ’ 1 4 0 9 100 โˆ’ 2 1000 โˆ’ 2 10 7 10 6 100 2 1000 2 10 2 100 0 1 4 + โˆš3 12 1 4 โˆ’ โˆš3 12 0 1 2 1 2 โˆ’ 2 10 7 10 6 100 โˆ’ 127 300 โˆ’ 1 100 3 5 โˆ’ 2 5 + 7โˆš3 30 2 5 + 7โˆš3 30 1 10 0 1 2 1 2 Moreover, from the 5๐‘กโ„Ž-order method, the coefficients of ๐ด and ๐ถ are computed, and a three-stage 4๐‘กโ„Ž-order embedded approach is then derived. The solution for ๐‘1 ๐‘‡ , ๐‘โ€ฒ2 ๐‘‡ and ๐‘โ€ฒโ€ฒ3 ๐‘‡ is obtained by simultaneously solving the equations up to order 5, while ๐‘โ€ฒโ€ฒโ€ฒ3 ๐‘‡ has the same result as the fifth order. The answers are attained as ๐‘โ€ฒ 1 ๐‘‡ = โˆ’ 1 12 + 2 5 ๐‘โ€ฒ 3 ๐‘‡ โˆ’ 2โˆš6 5 ๐‘โ€ฒ 3 ๐‘‡ + โˆš6 24 , ๐‘โ€ฒ 2 ๐‘‡ = โˆ’ 7 5 ๐‘โ€ฒ 3 ๐‘‡ + 2โˆš6 5 ๐‘โ€ฒ 3 ๐‘‡ โˆ’ โˆš6 24 + 1 4 , ๐‘โ€ฒ 3 ๐‘‡ = ๐‘โ€ฒ 3 ๐‘‡ , ๐‘1 ๐‘‡ = 1 24 โˆ’ ๐‘2 ๐‘‡ โˆ’ ๐‘3 ๐‘‡ , ๐‘2 ๐‘‡ = ๐‘2 ๐‘‡ , ๐‘3 ๐‘‡ = ๐‘3 ๐‘‡ , ๐‘โ€ฒโ€ฒโ€ฒ 1 ๐‘‡ = 1 9 , ๐‘โ€ฒโ€ฒโ€ฒ 2 ๐‘‡ = 4 9 โˆ’ โˆš6 36 , ๐‘โ€ฒโ€ฒโ€ฒ 3 ๐‘‡ = 4 9 + โˆš6 36 , ๐‘โ€ฒโ€ฒ 1 ๐‘‡ = 0, ๐‘โ€ฒโ€ฒ 2 ๐‘‡ = 1 4 + โˆš6 36 , ๐‘โ€ฒโ€ฒ 3 ๐‘‡ = 1 4 โˆ’ โˆš6 36 . We determine the free parameters according to [12] by minimizing the LTE using Maple's minimized command as follows: ๐‘โ€ฒ3 ๐‘‡= 0.0323023077253058, ๐‘2 ๐‘‡= -0.148646585401452 and ๐‘3 ๐‘‡= 0.447631755184810. If the value is optimized in fractional form, then ๐‘โ€ฒ3 ๐‘‡ = 3 100 , ๐‘2 ๐‘‡ = โˆ’ 1 10 , and ๐‘3 ๐‘‡ = 4 10 are chosen. IHJPAS. 37 (1) 2024 380 Table 4. The Embedded Pair EDIRKTO5(4) Method. 1 โˆ’ 3 10 โˆ’ 2 100 2 5 โˆ’ โˆš6 10 4 10 โˆ’ 3 10 279 25000 โˆ’ 381โˆš6 25000 โˆ’ 2 100 2 5 + โˆš6 10 โˆ’ 1 10 5 10 โˆ’ 3 10 โˆ’ 63 1000 + 39โˆš6 1000 9 100 โˆ’ 2 100 9 10000 1223 6000 + 1331โˆš6 180000 1223 6000 โˆ’ 1331โˆš6 180000 0 1 12 + โˆš6 48 1 12 โˆ’ โˆš6 48 0 1 4 + โˆš6 36 1 4 โˆ’ โˆš6 36 1 9 4 9 โˆ’ โˆš6 36 4 9 + โˆš6 36 โˆ’ 31 120 โˆ’ 1 10 2 5 โˆ’ 107 1500 + 89โˆš6 3000 26 125 โˆ’ 89โˆš6 3000 3 100 0 1 4 + โˆš6 36 1 4 โˆ’ โˆš6 36 1 9 4 9 โˆ’ โˆš6 36 4 9 + โˆš6 36 5. Problems Test The methods presented in section 4 were tested with four different problems in this section. The following techniques were used to carry out the numerical experiments: Problem 1. [15] (Inhomogeneous linear problem) ๐‘ž(4)(๐‘ก) = ๐‘žโ€ฒ(๐‘ก) โˆ’ cos (๐‘ก), ๐‘ž(0) = โˆ’ 1 2 , ๐‘žโ€ฒ(0) = 1 2 , ๐‘žโ€ฒโ€ฒ(0) = 1 2 , ๐‘žโ€ฒโ€ฒโ€ฒ(0) = โˆ’ 1 2 , where t โˆˆ [0,2], Exact solution is ๐‘ž(๐‘ก) = 1 2 sin(๐‘ก) โˆ’ 1 2 cos(๐‘ก). Problem 2. [15] (Homogeneous linear problem) ๐‘ž(4)(๐‘ก) = ๐‘ž2(๐‘ก) + (๐‘žโ€ฒ(๐‘ก))2 + sin(๐‘ก) โˆ’ 1, ๐‘ž(0) = 0, ๐‘žโ€ฒ(0) = 1, ๐‘žโ€ฒโ€ฒ(0) = 0 , ๐‘žโ€ฒโ€ฒโ€ฒ(0) = โˆ’1, Where t โˆˆ [0,1], The exact solution is ๐‘ž(๐‘ก) = sin (t). Problem 3. [15] (Homogeneous linear system) ๐‘ž1 (4)(๐‘ก) = โˆ’ ๐‘’3๐‘ก 4 ๐‘ž4 โ€ฒ (๐‘ก), ๐‘ž1(0) = 1, ๐‘ž1 โ€ฒ (0) = โˆ’1, ๐‘ž1 โ€ฒโ€ฒ(0) = 1, ๐‘ž1 โ€ฒโ€ฒโ€ฒ(0) = โˆ’1, ๐‘ž2 (4)(๐‘ก) = โˆ’16 ๐‘’โˆ’๐‘ก ๐‘ž1 โ€ฒ (๐‘ก), ๐‘ž2(0) = 1, ๐‘ž2 โ€ฒ (0) = โˆ’2, ๐‘ž2 โ€ฒโ€ฒ(0) = 4, ๐‘ž2 โ€ฒโ€ฒโ€ฒ(0) = โˆ’8, ๐‘ž3 (4)(๐‘ก) = โˆ’ 81 ๐‘’โˆ’๐‘ก 2 ๐‘ž2 โ€ฒ (๐‘ก), ๐‘ž3(0) = 1, ๐‘ž3 โ€ฒ (0) = โˆ’3, ๐‘ž3 โ€ฒโ€ฒ(0) = 9, ๐‘ž3 โ€ฒโ€ฒโ€ฒ(0) = โˆ’27, IHJPAS. 37 (1) 2024 381 ๐‘ž4 (4)(๐‘ก) = โˆ’ 356 ๐‘’โˆ’๐‘ก 4 ๐‘ž3 โ€ฒ (๐‘ก), ๐‘ž4(0) = 1, ๐‘ž4 โ€ฒ (0) = โˆ’4, ๐‘ž4 โ€ฒโ€ฒ(0) = 16, ๐‘ž4 โ€ฒโ€ฒโ€ฒ(0) = โˆ’64, where t โˆˆ [0,1], The exact solution is ๐‘ž1(๐‘ก) = ๐‘’โˆ’๐‘ก, ๐‘ž2(๐‘ก) = ๐‘’โˆ’2๐‘ก, ๐‘ž3(๐‘ก) = ๐‘’โˆ’3๐‘ก, ๐‘ž4(๐‘ก) = ๐‘’โˆ’4๐‘ก. Problem 4. [15] (Inhomogeneous nonlinear problem) ๐‘ž(4)(๐‘ก) = โˆ’ 15 ๐‘žโ€ฒ(๐‘ก) 8 ๐‘ž6(๐‘ก) , ๐‘ž(0) = 1, ๐‘žโ€ฒ(0) = 1 2 , ๐‘žโ€ฒโ€ฒ(0) = โˆ’ 1 4 , ๐‘žโ€ฒโ€ฒโ€ฒ(0) = 3 8 , Where t โˆˆ [0, ๐œ‹ 4 ], Exact solution is ๐‘ž(๐‘ก) = โˆš๐‘ก + 1. 6. Numerical Results The tables below show the approximation outcomes for resolving issues 1-4. In the tables, the following acronyms will be used: ๏‚ท Tol: Tolerance. ๏‚ท F. N: the function call's number ๏‚ท STEP: succeeded strides number ๏‚ท FSTEP: failure strides number ๏‚ท TIME: enforcement time ๏‚ท EDIRKTO4(3): the embedded 4(3) method constructed in this paper ๏‚ท EDIRKTO5(4): the embedded 5(4) method constructed in this paper Table 5. Problem 1-related numerical comparisons FSTEP STEP TIME F.N METHOD TOL(h) 0 7 0.068 21 EDIRKTO4(3) 10โˆ’2 0 5 0.029 15 EDIRKTO5(4) 0 19 0.081 57 EDIRKTO4(3) 10โˆ’4 2 14 0.036 46 EDIRKTO5(4) 1 70 0.102 212 EDIRKTO4(3) 10โˆ’6 2 43 0.045 133 EDIRKTO5(4) IHJPAS. 37 (1) 2024 382 Table 6. Problem 2-related numerical comparisons FSTEP STEP TIME F.N METHOD TOL(h) 0 4 0.068 12 EDIRKTO4(3) 10โˆ’2 0 3 0.038 9 EDIRKTO5(4) 1 11 0.088 35 EDIRKTO4(3) 10โˆ’4 0 7 0.068 21 EDIRKTO5(4) 1 34 0.096 104 EDIRKTO4(3) 10โˆ’6 0 23 0.077 69 EDIRKTO5(4) Table 7. Problem 3-related numerical comparisons FSTEP STEP TIME F.N METHOD TOL(h) 2 13 0.056 43 EDIRKTO4(3) 10โˆ’2 2 9 0.028 31 EDIRKTO5(4) 2 47 0.066 145 EDIRKTO4(3) 10โˆ’4 2 25 0.039 79 EDIRKTO5(4) 3 205 0.105 621 EDIRKTO4(3) 10โˆ’6 2 76 0.087 232 EDIRKTO5(4) Table 8. Problem 4-related numerical comparisons FSTEP STEP TIME F.N METHOD TOL(h) 1 4 0.080 14 EDIRKTO4(3) 10โˆ’2 0 2 0.056 6 EDIRKTO5(4) 1 10 0.089 32 EDIRKTO4(3) 10โˆ’4 1 6 0.057 20 EDIRKTO5(4) 2 36 0.098 112 EDIRKTO4(3) 10โˆ’6 1 18 0.060 56 EDIRKTO5(4) IHJPAS. 37 (1) 2024 383 Problem 1 Problem2 Problem 3 Problem 4 Figure 1. Competence curves for methods 7. Discussion In this paper, Figure 1 illustrates the enhancements made to the Implicit Type Runge-Kutta Method of Diagonally Embedded Pair (EDIRKTO). This was done by plotting the decimal logarithm for the time curve with the highest value against the logarithm of some function call estimates that were taken from Tables 5-8. The current study comparison of EDIRKTO4(3) and EDIRKTO5(4) with the four different problems. Furthermore, Figure 1 was made using the corresponding numerical results from Tables 5โ€“8, respectively. In addition, as shown in Tables 5- 8, computations of the succeeded stride number (Step) and the failure stride number (FSTEP). Figure 1 illustrates the numerical comparison between the EDIRKTO4(3) and EDIRKTO5(4) outcomes from the current study. The current study is based on the Runge-Kutta Method, which has been previously studied by [4, 5, 8]. However, the research at hand broadened and enhanced the method from explicit to implicit and from direct to diagonal. 8. Conclusion The solution of fourth ODEs using diagonally embedded implicit Runge-Kutta methods has been discussed in this paper. Numerical findings demonstrate that the suggested approaches are much more effective in terms of the number of function evaluations while solving the general 4th- order ODEs. IHJPAS. 37 (1) 2024 384 Acknowledgment The authors are greatly appreciated the referees for their valuable comments and suggestions for improving the paper Conflict of Interest The authors declare that they have no conflicts of interest. Funding There is no financial support in preparation for the publication. References 1. Alomari, A.; Anakira, N.R.; Bataineh, A.S.; Hashim, I. Approximate solution of nonlinear system of BVP arising in fluid flow problem. Mathematical Problems in Engineering, 2013, 2013,1-7. 2. Jator, S.N. Numerical integrators for fourth order initial and boundary value Problems. International Journal of Pure and Applied Mathematics, 2008, 47(4), 563โ€“576. 3. 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