Inter national J our nal of Electrical and Computer Engineering (IJECE) V ol. 10, No. 2, April 2020, pp. 2192 2199 ISSN: 2088-8708, DOI: 10.11591/ijece.v10i2.pp2192-2199 r 2192 The best sextic appr oximation of h yperbola with order twelv e Abedallah Rababah 1 , Esra’a Rababah 2 1 Department of Mathematical Sciences, United Arab Emirates Uni v ersity , Al Ain, U AE 1,2 Department of Mathematics, Jordan Uni v ersity of Science and T echnology , Jordan Article Inf o Article history: Recei v ed Apr 8, 2019 Re vised Oct 20, 2019 Accepted No v 2, 2019 K eyw ords: approximation order equioscillation high accurac y h yperbola se xtic parametric approximation ABSTRA CT In this article, the best uniform approximation for the h yperbola of de gree 6 that has approximation order 12 is found. The associated error function v anishes 12 times and equioscillates 13 times. F or an arc of the h yperbola, the error is bounded by 2 : 4 10 4 . W e e xplain the details of the deri v ation and sho w ho w to apply the method. The method is simple and this encourages and moti v ates people w ork- ing in CG and CAD to apply it in their w orks. Copyright c 2020 Insitute of Advanced Engineeering and Science . All rights r eserved. Corresponding A uthor: Abedallah Rababah, Department of Mathematical Sciences, United Arab Emirates Uni v ersity , Al Ain, U AE. Department of Mathematics, 22110 Irbid, Jordan. Email: rababah@uaeu.ac.ae and esrababah15@sci.just.edu.jo 1. INTR ODUCTION B ´ ezier curv es were in v ented by Pierre B ´ ezier and P aul de Casteljau in the 1960’ s. The primary application w as in the automobile industry , b ut today the y are widely used in man y computer applications and codes to sk etch curv es. Approximation using polynomials of lo w de gree is f a v ourable, and in man y cases is a must issue. Man y CAD systems are limited to using only parametric polynomial curv es of lo w de gree with lo w errors. The big error causes tw o major disadv antages: high accumulated error , and slo w and costly softw are. So, it is f a v ourable to approximate using lo w de gree polynomi als. P arabolas are represented e xactly using parametric curv es of de gree 2. In [1] methods of best uniform approximation of a circular arc of de gree 6 with order 12 are accomplished. These approximations are optimal and ha v e 13 equioscillations. In [2], a method of best uniform approximation of a h yperbola of de grees 2 with order 4 is accomplished. These results were moti v ated by the results of approximating curv es with high accurac y [3-6]. In this paper , we find approximation for the h yperbola of de gree 6 and we get the order 12 . B ´ ezier curv e techniques are used to represent the approximations of the h yperbola using parametric polynomials of de gree 6 that ha v e the least uniform error . The method is simple and practical. T o achie v e this approximation, proper arrangements and symmetries of the h yperbola are applied to determine the B ´ ezier points that define the approximation of the h yperbola, and therefore, mak es a CAD system more ef ficient and minimizes the cost. Using suitable translation and scaling, the h yperbola can be written in the basic forms: y 2 x 2 = 1 and x 2 y 2 = 1 . Ev ery form has tw o branches. So, there are four branches. Geometrically , all of these branches J ournal homepage: http://ijece .iaescor e .com/inde x.php/IJECE Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Elec & Comp Eng ISSN: 2088-8708 r 2193 are identical. Therefore, it is suf ficient to represent one branch and the other three branches can be represented using rotation of this branch. So, we consider the upper branch of the h yperbola y 2 x 2 = 1 , see Figure 1. It can be written in parametric form c : t 7! (sinh( t ) ; cosh( t )) ; t 2 < . W e are interested in finding out the longest arc of the h yperbola that can be approximate d and that the error function is the Chebyshe v polynomial, see [2]. It is impossible to e xactly repres ent a h yperbola with a polynomial curv e [7-11]. It can be represented e xactly using rational B ´ ezier curv es, a polynomial parametric form is preferred in man y applications. The ability to represent a primiti v e h yperbola is a must issue especia lly in computer graphics and data and image processing. Thus, there is a demand to find a parametrically defined polynomial curv e p 6 : t 7! ( x 6 ( t ) ; y 6 ( t )) ; 0 t 1 , where x 6 ( t ) ; y 6 ( t ) are polynomials of de gree 6 . The p 6 has to approximate c within tolerable error . In this paper , de gree 6 parametric curv es are considered, and it is sho wn that the error is v ery small and the results are competiti v e. - 20 - 10 10 20 - 20 - 10 10 20 Figure 1. The Hyperbola y 2 x 2 = 1 The Euclidean error function is used to measure the error between p 6 and c . The error is defined by : E ( t ) := q y 2 6 ( t ) x 2 6 ( t ) 1 : (1) E ( t ) is replaced by the follo wing error function: e ( t ) := y 2 6 ( t ) x 2 6 ( t ) 1 : (2) The approximation problem is formulated as follo ws. The appr oximation pr oblem is to find p 6 : t 7! ( x 6 ( t ) ; y 6 ( t )) ; 0 t 1 , where x 6 ( t ) ; y 6 ( t ) are polynomials of de gree 6 , that approximates c by satisfying the follo wing three conditions: (a) p 6 minimizes max t 2 [0 ; 1] j e ( t ) j , (b) p 6 approximates c with order twelv e [12], (c) e ( t ) equioscillates thirteen times o v er [0 ; 1] . The solution to this problem is sho wn in section 3 . This sol ution is presented in Figure 2 and Figure 3; the corresponding error is sho wn in Figure 4. More related results can be found in [13-15] and the references therein. The best se xtic appr oximation of ... (Abedallah Rababah) Evaluation Warning : The document was created with Spire.PDF for Python.
2194 r ISSN: 2088-8708 21 - 21 21 Figure 2. The Hyperbola and the se xtic approximating B ´ ezier curv e Figure 3. Zoom in the b usy part of Figure 2 0.2 0.4 0.6 0.8 1.0 t - 0.0004 - 0.0002 0.0002 0.0004 e H t L Figure 4. The error of the se xtic approximating B ´ ezier curv e 2. RESEARCH METHOD Let p 6 ( t ) = ( x 6 ( t ) ; y 6 ( t )) be a se xtic polynomial parametric representat ion of the curv e c . In CA GD, curv es are presented using the B ´ ezier form, see Figure 5 for possible choice of the B ´ ezier points. P 0 P 1 P 2 P 3 P 4 P 5 P 6 21 - 21 21 Figure 5. Possible B ´ ezier points of the h yperbola The B ´ ezier curv e p 6 ( t ) has the follo wing form: p 6 ( t ) = 6 X i =0 p i B 6 i ( t ) =: x 6 ( t ) y 6 ( t ) ; 0 t 1 ; (3) where p 0 ; p 1 ; p 2 ; p 3 ; p 4 ; p 5 ; p 6 are the B ´ ezier points, and the Bernstein polynomial basis of de gree 6 is defined by: B 6 i ( t ) = 6 i (1 t ) 6 i t i ; i = 0 ; : : : ; 6 ; t 2 [0 ; 1] : Int J Elec & Comp Eng, V ol. 10, No. 2, April 2020 : 2192 – 2199 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Elec & Comp Eng ISSN: 2088-8708 r 2195 The simplicity of this method should encourage people w orking in the fields of Computer Graphics, Image Processing, CAD, and Data Processing to adopt it in their design and applications. The symmetry in the h yperbola is used to better locate the B ´ ezier points. W e be gin by letting p 0 = ( ; ) . The h yperbola is symmetric around the y -axis, so, to obe y this symmetry , the point p 6 should ha v e the form p 6 = ( ; ) . The point p 1 = ( ; ) , so, to obe y the symmetry , the point p 5 should ha v e the form p 5 = ( ; ) . The point p 2 = ( ;   ) , so, to obe y the symmetry , the point p 4 should ha v e the form p 4 = ( ;   ) . There is one remaining point; if this point lies in either halv es of the plane around the y -axis, then the symmetry of the h yperbola i s kick ed. Thus, the point p 3 must lie on the y -axis and has the form p 3 = (0 ; ! ) . Therefore, the proper choice for the B ´ ezier points is p 0 = ; p 1 = ; p 2 =   ; p 3 = 0 ! ; p 4 =   ; p 5 = ; p 6 = : (4) The B ´ ezier polynomial curv e p 6 ( t ) in (3) is gi v en in the form 0 @ x 6 ( t ) y 6 ( t ) 1 A = 0 @ B 6 0 ( t ) B 6 1 ( t ) B 6 2 ( t ) + B 6 4 ( t ) + B 6 5 ( t ) + B 6 6 ( t ) B 6 0 ( t ) + B 6 1 ( t ) +   B 6 2 ( t ) + ! B 6 3 ( t ) +   B 6 4 ( t ) + B 6 5 ( t ) + B 6 6 ( t ) 1 A ; (5) where 0 t 1 . The se v en parameters ; ; ; ; ;   ; ! are used to ha v e the polynomial approximation p 6 comply with the conditions of the approximation problem; this is done in the follo wing section. 3. RESUL TS AND AN AL YSIS The v alues of ; ; ; ; ;   ; ! that minimize the uniform error and satisfy the conditions of the approximation problem are gi v en in the follo wing theorem. A symbolic programming language is used to get the v alues of the parameters in (4) and are rounded in decimal form. Theor em 1: The B ´ ezier curv e in (5) with the B ´ ezier points in (4), where = 21 : 396696163346007 ; = 21 : 420062908119476 ; = 0 : 34812943434024657 ; = 0 : 3015887594987887 ; = 0 : 5937616113806532 ;   = 0 : 705589524343983 ; ! = 0 : 1813438330271954 (6) satisfies the three conditions of the Approximation Problem. More precisely , the error functions satisfy: 1 2 11 e ( t ) 1 2 11 ; 1 2 11 (2 ) E ( t ) 1 2 11 (2 + ) ; where = max 0 t 1 j E ( t ) j : (7) Pr oof: From equation (5), we get x 6 ( t ) = B 6 6 ( t ) B 6 0 ( t ) + B 6 5 ( t ) B 6 1 ( t ) + B 6 4 ( t ) B 6 2 ( t ) ; y 6 ( t ) = B 6 6 ( t ) + B 6 0 ( t ) + B 6 5 ( t ) + B 6 1 ( t ) +   B 6 4 ( t ) + B 6 2 ( t ) + ! B 6 3 ( t ) : Substituting x 6 ( t ) and y 6 ( t ) into the error function e ( t ) in (2) and re writing the result in terms of po wers of t we get the follo wing equality: e ( t ) = t 12 4 2 48 + 144 2 + 120 720 + 900 2 80 ! + 480 ! 1200 ! + 400 ! 2 + t 11 24 2 + 288 864 2 720 + 4320 5400 2 + 480 ! 2880 ! + 7200 ! 2400 ! 2 + t 10 36 2 + 288 576 2 360 + 1440 900 2 + 96 2 1032 + 2736 2 +2400   12600   + 14400   2 1560 ! + 8160 ! 18600   ! + 6000 ! 2 + t 9 180 2 1440 + 2880 2 + 1800 7200 + 4500 2 260 2 + 2520 5760 2 The best se xtic appr oximation of ... (Abedallah Rababah) Evaluation Warning : The document was created with Spire.PDF for Python.
2196 r ISSN: 2088-8708 5400   + 23400   22500   2 + 3400 ! 14400 ! + 27000   ! 8000 ! 2 + t 8 465 2 + 3480 6480 2 4170 + 15480 9225 2 + 525 2 4440 +8640 2 + 8430   29880   + 22725   2 5040 ! + 17040 ! 24000   ! + 6000 ! 2 + t 7 780 2 5280 + 8640 2 + 5880 18720 + 9900 2 804 2 + 5808 9504 2 9240   + 26640   15300   2 + 5040 ! 13440 ! + 13200   ! 2400 ! 2 + t 6 922 2 + 5460 7488 2 5460 + 13860 5850 2 + 926 2 5628 +7632 2 + 7140   16380   + 6750   2 3360 ! + 6720 ! 4200   ! + 400 ! 2 + t 5 792 2 3948 + 4320 2 + 3360 6300 + 1800 2 792 2 + 3972 4320 2 3840   + 6660   1800   2 + 1440 ! 1920 ! + 600   ! + t 4 495 2 + 1980 1620 2 1320 + 1620 225 2 + 495 2 1980 + 1620 2 +1380   1620   + 225   2 360 ! + 240 ! + t 3 220 2 660 + 360 2 + 300 180 220 2 + 660 360 2 300   +180   + 40 ! ) + t 2 66 2 + 132 36 2 30 + 66 2 132 + 36 2 + 30   + t 12 2 12 12 2 + 12 + ( 1 2 + 2 ) : W e substitute the v alues of ; ; ; ; ;   and ! from (6) into the last equation to get e ( t ) = 4096 t 12 24576 t 11 + 64512 t 10 97280 t 9 + 93024 t 8 58752 t 7 + 24752 t 6 6864 t 5 + 19305 16 t 4 1001 8 t 3 + 429 64 t 2 9 64 t + 1 2048 ; t 2 [0 ; 1] : Making the substitution t = u +1 2 reduces the error function to the follo wing form e ( u ) = 1 2048 9 256 u 2 + 105 256 u 4 7 4 u 6 + 27 8 u 8 + 3 t 10 + t 12 ; u 2 [ 1 ; 1] : The last form of e ( u ) coincides with the monic Chebyshe v polynomial ~ T 12 ( u ) ; u 2 [ 1 ; 1] , which is the unique polynomial of de gree 12 that equioscillates 13 times between 1 2 11 for all u 2 [ 1 ; 1] and has the least de viation [12]. This sho ws that p 6 satisfies the conditions of the approximation problem. The error formula for E ( t ) can be pro v ed using its relation to the error function e ( t ) . This pro v es Theorem 1. It is clear that the approximation is the best uniform approximation from Figure 4. Figure 2 and Figure 3 sho w the h yperbola and the approximating B ´ ezier curv e, Figure 4 sho ws the corresponding error , and Figure 6 sho ws the Euclidean error . 4. CONCLUSION In this paper , the best uniform approximation of the h yperbola with parametrically defined polyno- mial curv es of de gree 6 are e xplicitly gi v en. The error function equioscillates 13 times; the approximation order is 12 . The method of construction demonstrates the ef ficienc y and simplicity of the approximation method. The approximation intersects the h yperbola 12 times with maximum error 2 : 4 10 4 . Reflecting the upper branch of the h yperbola around the x -axis gi v es the l o wer branch. The h yperbola is sho wn in Figure 7. Note t hat the points p 1 ( p 5 ) and p 2 ( p 4 ) i n both branches are v ery close to each other and can not be distin- guished from each other . The results in this paper can be used to impro v e the results obtained in [16-23] see also the results in [24, 25]. Int J Elec & Comp Eng, V ol. 10, No. 2, April 2020 : 2192 – 2199 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Elec & Comp Eng ISSN: 2088-8708 r 2197 0.2 0.4 0.6 0.8 1.0 t - 0.0002 - 0.0001 0.0001 0.0002 E H t L Figure 6. The Euclidean error of the se xtic B ´ ezier curv e 21 - 21 21 - 21 - 21 21 Figure 7. Both branches of the Hyperbola using tw o B ´ ezier curv es A CKNO WLEDGMENTS The authors o we thanks for the re vie wers for in v aluable sugges tions to impro v e an e arlier v ersion of this paper . This research w as funded by Jordan Uni v ersity of Science and T echnology . REFERENCES [1] A. Rababah, ”Best se xtic approximation of circular arcs with thirteen equioscillations, ” Pro- ceedings of the Jangjeon Mathematical Societ y , v ol. 21, Issue 1, pp. 111–123, 2018. DOI: http://doi.or g/10.17777/pjms2018.21.1.111 [2] A. Rababah, ”The Best Quadratic Approximation of Hyperbola with Order F our , ” Journal of Inequalities and Special Functions , v ol. 7, Issue 3, pp. 1–11, 2016. [3] M. Floater , ” High order approximation of conic sections by quadratic splines, ” Computer Aided Geomet- ric Design , v ol. 12, pp. 617–637, 1995. [4] C. de Boor ., et al., ”High accurac y geometric Hermite interpolation, ” Computer Aided Geometric Design , v ol. 4, pp. 269–278, 1988. [5] A. Rababah, ”T aylor theorem for planar curv es, ” Proceedings of the American Mathematical Society , v ol. 119, Issue 3, pp. 803–810, 1993. [6] A. Rababah, ”High accurac y Hermite approximation for space curv es in < d , ” Journal of Mathematical Analysis and Applications , v ol. 325, Issue 2, pp. 920–931, 2007. [7] K. H ¨ ollig and J. H ¨ orner , ”Approximation and Modeling with B-Splines, ” SIAM, T itles i n Applied Math- ematics , v ol. 132, 2013. [8] H. Prautzsch., et al., ”B ´ ezier and B-Spline T echniques, ” Springer 2002. The best se xtic appr oximation of ... (Abedallah Rababah) Evaluation Warning : The document was created with Spire.PDF for Python.
2198 r ISSN: 2088-8708 [9] P . B ´ ezier , ”The mathematical basis of the UNISURF CAD system, ” Butterw orth-Heinemann Ne wton , MA, USA, ISBN 0-408-22175-5, 1986. [10] Carl de Boor , A Practical Guide to Splines, Series T itle: Applied Mathematical Sciences, V ol 27, Springer - V erlag Ne w Y ork, 1978. [11] Gerald F arin, Curv es and surf aces for computer -aided geometric design: a practical guide. Else vier , 2014. [12] J. Rice, ”The approximation of functions, ” linear theory , Addison-W esle y , v ol. 1, 1964. [13] Y . J. Ahn and C. Hof fmann, ”Circle approximation using LN B ´ ezier curv es of e v en de gree and its ap- plication, ” Journal of Mathematical Analysis and Applications , v ol. 410 Issue 1, pp. 257–266, February 2014. [14] S. W . Kim and Y . J. Ahn, ”Circle approximation by quartic G 2 spline using alternation of error function, ” J. KSIAM , v ol. 17, Issue 5, pp. 171–179, 2013. [15] A. Rababah., et al., ”Multiple De gree Reduction and Ele v ation of B ´ ezier Curv es Using Jacobi-Bernstein Basis T ransformations, ” Numerical Functional Analysis and Opt imization , v ol. 28, Issue 9-10, pp. 1179– 1196, 2007. [16] S. Alabed, ”Performance Analysis of Dif ferential Beamforming in Decentralized Netw orks, ” Interna- tional Journal of Electrical and Computer Engineering (IJECE) , v ol. 8 Issue 3, pp. 1692-1700, 2018. DOI: http://doi.or g/10.11591/ijece.v8i3.pp1692-1700 [17] C. Suw annapong and C. Khunboa, ”An Approximation Delay betwee n Consecuti v e Requests for Con- gestion Control in Unicast CoAP-based Group Communication, ” International Journal of Electrical and Computer Engineering (IJECE) , v ol. 9, Issue 3, June 2019. DOI: http://doi.or g/10.11591/ijece.v9i3. [18] Bhar g a v Bhatkalkar , Abhishek Joshi, Srikanth Prabhu, Sulatha Bhandary , Automated fundus image qual- ity assessment and se gmentation of optic disc using con v olutional neural netw orks. International Journal of Electrical and Computer Engineering (IJECE) V ol.10, No.1, 2020, pp. 816 827, ISSN: 2088-8708, DOI: 10.11591/ijece.v10i1.pp816-827. [19] Rodiah, Sarifuddin Madenda, Diana T ri Susetianigtias, De wi Agushinta Rahayu, EtySutanty , Optic Disc and Macula Localization from Retinal Optical Coherence T omograph y and Fundus Image, International Journal of Electrical and Computer Engineering (IJECE) V ol.8, No.6, 2018, pp. 5050-5060, ISSN: 2088- 8708, DOI: 10.11591/ijece.v8i6.pp5050-5060. [20] G. Da w ay , Hana H. kareem, Ahmed Rafid Hashim, Pupil Detection Based on Color Dif ference and Circu- lar Hough T ransformHazim, International Journal of Electrical and Computer Engineering (IJECE) V ol.8, No.5, 2018, pp. 3278-3284, ISSN: 2088-8708, DOI: 10.11591/ijece.v8i5.pp3278-3284. [21] A. R ababah, L-2 de gree reduction of triangular B ´ ezier surf aces with common tangent planes at v er - tices. International Journal of Computational Geometry & Applications, V ol. 15, No. 5 (2005) 477-490. http://www .w orldscinet.com/ijcg a/15/1505/S02181959051505.html [22] A. Rababah, Distances with rational triangular B ´ ezier surf aces. Applied Mathematics and Computation 160, ( 2005 ) 379-386. http://www .else vier .com/locate/amc [23] A. Rababah and Moath Jaradat, Approximating of fset Curv es using B ´ ezier curv es with high accurac y , International Journal of Electrical and Computer Engineering (IJECE) V ol.10, No.2, 2020 (P AR T I). [24] A. Rababah, ”Approximation v on K urv en mit Polynomen und Splines, ” Ph. Dissertation, Stuttg art Uni- v ersit ¨ at , W est German y , 1992. [25] A. Rababah, The best quintic Chebyshe v approximation of circular arcs of order ten, International Journal of Electrical and Computer Engineering (IJECE)V ol. 9, No. 5, October 2019, pp. 3779-3785, ISSN: 2088- 8708, DOI: 10.11591/ijece.v9i5.pp3779-3785. Int J Elec & Comp Eng, V ol. 10, No. 2, April 2020 : 2192 – 2199 Evaluation Warning : The document was created with Spire.PDF for Python.
Int J Elec & Comp Eng ISSN: 2088-8708 r 2199 BIOGRAPHIES OF A UTHORS Abedallah Rababah is a professor of mathematics at United Arab Emirates Uni v ersity and is on lea v e from Jordan Uni v ersity of Science and T echnol ogy . He is w orking in the field of Computer Aided Geometric Design, abbre viated CA GD. In particular , his rese arch is on de gree raising and reduction of B ´ ezier curv es and surf aces with geometric boundary conditions, Bernstein polynomials, and their duality . He is kno wn for his research in describing approximation methods that significantly impro v e the standard rates obtained by classical (local T aylor , Hermite) methods. He pro v ed the fol- lo wing conjecture for a particular set of curv es of nonzero measure: Conjecture: A smooth re gular planar curv e can, in general, be approximated by a polynomial curv e of de gree n wi th order 2n. The method e xploited the freedom in the choice of the parametrization and achie v ed the order 4n/3, rather than n + 1. Generalizations were also pro v ed for space curv es. Professor Rababah is also do- ing research in the fields of classical approximation theory , orthogonal polynomials, Jacobi-weighted orthogonal polynomials on triangular domains, and best uniform approximations. Since 1992, He has been teaching at German, Jordanian, American, Canadian, and Emirates’ uni v ersities. He is acti v e in the editorial boards of man y journals in mathematics and computer science. Further info can be found on his homepage at ResearchGate: https://www .researchg ate.net/profile/Abedallah Rababah or at http://www .just.edu.jo/eportfolio/P ages/Def ault.aspx?email=rababah Esra’a Rababah graduated from Jordan Uni v ersity of Science and T echnology . She obtained both Bachelor and Master De grees in Mathematics with research interests in the field of numerical analy- sis, a pproximation theory , and B ´ ezier techniques. She w ork ed as teacher assistant at Jordan Uni v er - sity of Science and T echnology . Further info can be found on her homepage at ResearchGate: https://www .researchg ate.net/profile/Esraa Rababah The best se xtic appr oximation of ... (Abedallah Rababah) Evaluation Warning : The document was created with Spire.PDF for Python.