This page contains a list of all issues (papers and their authors) published in this journal before putting the journal into the OJS system. The papers can be downloaded as pdf documents.
Vol. 28, (2013)

Vol. 28, No 4 (2013)
 Predrag Rajković
A Tribute to Professor Ljiljana Petković’s 60th Anniversary  Ljiljana D. Petković and Mimica R. Milošević
Improved Higher Order Method for the Inclusion of Multiple Zeros of Polynomials  Carsten Carstensen
A Note on Matrix Methods for Location of the Zeros of Polynomials  Sladjana D. Marinković, Predrag M. Rajković and Miomir S. Stanković
The q–Iterative Methods in Numerical Solving of Some Equations with Infinite Products  Marko D. Petković and Nenad Živić
The Fekete Problem and Construction of the Spherical Coverage by Cones  Dušan M. Milošević, Miodrag S. Petković and Mimica R. Milošević
On an Interval Method for the Inclusion of One Polynomial Zero  Lidija Z. Rančić
Point Estimation of Cubically Convergent Root Finding Method of Weierstrass’ Type  Jovana Džunić
Modified Newton’s Method With Memory
 Predrag Rajković

Vol. 28, No 3 (2013)
 Arindam Sarkar and Paulomi Chattopadhyay
Further Results on a Unique Set of Meromorphic Functions with Different Poles  A. Sarkar and Dipankar Biswas
Legendre Curves on ThreeDimensional Heisenberg Groups  M. Fashandi
Compact Operators on Quaternionic Hilbert Spaces  Muhammad Amer Latif and Sever S. Dragomir
Some HermiteHadamard type Inequalities for Functions whose Partial Derivatives in Absloute Value are Preinvex on the Cooordinates  Lev A. Kazakovtsev
Algorithm for Constrained Weber Problem with Feasible Region Bounded by Arcs  M. El Hamma, R. Daher and A. Khadari
On Estimates for the Dunkl Transform in the Space L^{2}(R^{d},w_{k}(x)dx)  M. Emin Ozdemir, Mevlut Tunc and Ahmet Ocak Akdemir
On Some New Hadamardlike Inequalities for Coordinated sConvex Functions  Rashwan A. Rashwan and Samera M. Saleh
A Common Fixed Point Theorem of Three (ψ, φ)Weakly Contractive Mapping in Gmetric spaces  Bilall I. Shaini and Fatmir Hoxha
Computing Generalized Inverses Using Matrix Factorizations
 Arindam Sarkar and Paulomi Chattopadhyay

Vol. 28, No 2 (2013)
 George A. Anastassiou
Generalised Fractional HermiteHadamard inequalities involving mConvexity and (s,m)convexity  B. Barua and U. C. De
Characterizations of a Riemannian Manifolds admitting Ricci Solitions  Mohamed Houas and Zoubir Dahmani
New Results for a Coupled System of Fractional Differential Equations  Yan Wang, ShuHongWang, and Feng Qi
Simpson type Integral Inequalities in which the Power of the Absolute Value of the First Derivative of the Integrand is sPreinvex  Kamal Moro, Mohammed Fakir, Badr Dine El Kessab, Belaid Bouikhalene and Cherki Daoui
Comparison of two Feature Extraction Methods Based on the Raw and his Skeleton for Gujarati HandWritten Digits  Mitropam Chakraborty and Syamal Kumar Samanta
On a Fixed Point Theorem for a Cyclical Kannantype Mapping  Javad Laali and Mohammad Fozouni
Some Properties of Functional Banach Algebra  Hassen Aydi, Sunny Chauhan and Stojan Radenović
Fixed Points of weakly Compatible Mappings in GMetric Spaces Satisfying Common Limit Range Property  P. Titus and K. Ganesamoorthy
Forcing Detour Monophonic Number of a Graph  Yue Cheng and Ancheng Chang
Boundedness of Toeplitz Type Operator Associated to Singular Integral Operator on Lp spaces with Variable Exponent
 George A. Anastassiou

Vol. 28, No 1 (2013)
 Abhijit Banerjee and Sujoy Majumder
On Unique Range Set of Meromorphic Functions with Deficient Poles  Benharrat Belaïdi and Habib Habib
On the Growth of Solutions to Nonhomogeneous Linear Differential Equations wth Entire Coefficients Having the same Order  Igor Ševo
Probability Graphs  A. Abouelaz, R. Daher and M. El Hamma
Generalization of Titchmarsh’s Theorem for the Jacobi Transform  Milica D. Cvetković
Curvature Based Functions Variations  Nacima Memić
A Note on Multipliers of Weak Type on the Dyadic Group  Milan B. Tasić, Ivan P. Stanimirović
Simplifications of Rational Matrices by Using UML  Sadegh Tofigh, Alireza Morsali, Mohammad Askarizade and Hossein Momenaee Kermani
Field Extension and Designing a New 2 × 2 FullDiversity, FullRate and Information Loseless SpaceTime Block Code  Pradip Majhi and U. C. De
On Weak Symmetries of KahlerNorden Manifolds
 Abhijit Banerjee and Sujoy Majumder
Vol. 27, (2012)

Vol. 27, No 3 (2012)
 Daqing Lu
SHARP ESTIMATES AND BOUNDEDNESS FOR MULTILINEAR INTEGRAL OPERATORS  U. C. De and Pradip Majhi
CERTAIN CURVATURE PROPERTIES OF GENERALIZED SASAKIANSPACEFORMS  M. Alamgir Khan, Sumitra and Sunny Chauhan
COMMON FIXED POINT THEOREMS IN G* MENGER PMSPACES  Tan Lu, Chuangxia Huang and Lanzhe Liu
CONTINUITY ON BESOV SPACES OF MULTILINEAR COMMUTATOR OF SINGULAR INTEGRAL OPERATOR WITH VARIABLE CALDERÓNZYGMUND KERNEL  Nagat. M. Mustafa and Maslina Darus
SOME PROPERTIES OF A SUBCLASS OF ANALYTIC FUNCTIONS DEFINED BY A GENERALIZED SRIVASTAVAATTIYA OPERATOR  Muhammad Amer Latif and Sabir Hussain
SOME NEW HERMITEHADAMARD TYPE INEQUALITIES FOR FUNCTIONS WHOSE HIGHER ORDER PARTIAL DERIVATIVES ARE COORDINATED COVEX  Talat Körpinar and Essin Turhan
ON M2 SURFACES OF BIHARMONIC BGENERAL HELICES ACCORDING TO BISHOP FRAME IN HEISENBERG GROUP Heis^{3}  Xiaosha Zhou
SHARP WEIGHTED BOUNDEDNESS FOR VECTORVALUED MULTILINEAR SINGULAR INTEGRAL OPERATOR  Abimbola M. Jubril
A NONLINEAR WEIGHTS SELECTION IN WEIGHTED SUM FOR CONVEX MULTIOBJECTIVE OPTIMIZATION
 Daqing Lu

Vol. 27, No 2 (2012)
 Ali Abkar and Elahe Najafi
MSTEP ITERATIVE PROCESS FOR A FINITE FAMILY OF MULTIVALUED GENERALIZED NONEXPANSIVE MAPPINGS IN CAT(0)SPACES  Ahmed Anber, Zoubir Dahmani and Berrabah Bendoukha
NEW INTEGRAL IN EQUALITIES OF FENG QI TYPE VIA RIEMANNLIOUVILLE FRACTIONAL INTEGRATION  Talat Korpinar and Essin Turhan
ON PEDAL CURVES OF NORMAL SURFACES OF BIHARMONIC CURVES IN SL2(R)  Predrag S. Stanimirović, Marija S. Ćirić, Lev A. Kazakovtsev, Idowu A.Osinuga
SINGLEFACILITY WEBER LOCATION PROBLEM BASED ON THE LIFT METRIC  Mehmet Zeki Sarikaya
OSTROWSKI TYPE INEQUALITIES INVOLVING THE RIGHT CAPUTO FRACTIONAL DERIVATIVES BELONG TO Lp  Nacima Memić and Samra Pirić
INVERSE CHARACTER FORMULA FOR VILENKIN SYSTEMS  Muzafer Saračević, Predrag Stanimirović, Sead Mašović, Enver Biševac
IMPLEMENTATION OF THE CONVEX POLYGON TRIANGULATION ALGORITHM  Weiping Kuang
SHARP FUNCTION ESTIMATE FOR VECTORVALUED MULTILINEAR COMMUTATOR OF FRACTIONAL AREA INTEGRAL OPERATOR  Lev A. Kazakovtsev
ADAPTATION OF THE PROBABILITY CHANGING METHOD FOR WEBER PROBLEM WITH AN ARBITRARY METRIC
 Ali Abkar and Elahe Najafi

Vol. 27, No 1 (2012)
 A. Abkar and B. S. Choudhury
Fixed point results in partially ordered metric spaces using weak contractive inequalities  B. D. Pandey and B. Kunwar
Inverse and saturation theorems for linear combinations of a new class of positive linear operators  I. B. Grozdanović, N. I. Burić, K. D. Todorović and N. T. Vasović
Coupled stochastic oscilators with delays in coupling  I. Stojanović, P. S. Stanimirović and M. Miladinović
Applying the algorithm of Lagrange multipliers in digital image restoration  I. P. Stanimirović
Compendious lexicographic method for multiobjective optimizattion  E. Set, M. E. Özdemir and M. Z. Sarikaya
New inequalities of Ostrowski’s type for sconvex functions in the second sence with applications  M. A. Latif and S. S. Dragomir
Some companions of Fejer’s inequality for coordinated convex functions  Q. Xiao, X. Hu and L. Zhang
The reflexive extremal rank solutions to the matrix equation AX = B  A. Roukbi
Dragomir’s, Buzano’s and Kurepa’s inequalities in Hilbert C*modules  T. Qingshan
Continuity for multilinear commutator of BochnerRiesz operator on Besov spaces
 A. Abkar and B. S. Choudhury
Vol. 26, (2011)
 M. Darus and I. Faisal
Differential subordination for meromorphic multivalent quasiconvex functions  P. He
The uniqueness theorem for meromorphic functions sharing a set  S. Stanimirović
A generalization of the Pascal matrix and its properties  S. Ying, H. Chuangxia and L. Lanzhe
Sharp maximal function and Morrey spaces estimates for multilinear commutator of singular integral operators with nonsmooth kernels  I.P. Stanimirović, M.Lj. Zlatanović and M.D. Petković
On the linear weighted sum method for multiobjective optimization  P.V. Protić
Some remarks of medial grupoids
Vol. 25, (2010)
 X. F. Zhu, Y. L. Zhou, and W. T. Xiong
Characterizations of right ring congruences on a semiring  C. Mortici
A direct proof of the connection of two convergence tests  N. I. ĐuranovićMiličić and M. GardaševićFilipović
A multistep curve search algorithm in nonlinear optimization  M. B. Tasić and I. P. Stanimirović
Implementation of the partitioning method  S. H. Pepić
Weighted MoorePenrose inverse: PHP vs. MATHEMATICA  P.S. Stanimirović and M. Ćirić
Discrete location problem on arbitrary surface in R^{3}
Vol. 24, (2009)
 M. Ćirić, J. Ignjatović, and Ž. Popović
Stojan M. Bogdanović – scientist, teacher, and poet  M. Alomari and M. Darus
Fejér inequality for double integrals  N. V. Stojković and P. S. Stanimirović
Finite termination and decreasing dimensions in Mehrotra's primaldual algorithm  I. P. Stanimirović and M. B. Tasić
Performance comparison of storage formats for sparse matrices  S. V. Vukašinović, P. S. Stanimirović, M. D. Petković, and M. D. Ćirić
Turing machine and its symbolic simulation
Vol. 23, (2008)
 B.G Pachpatte
On Certain Volterra Integral and IntegroDi erential Equations  M. Tilca
A KFunctional Characterization of the Spline Approximation  C. Radu
Variation Detracting Property of the Bezier Type Operators  G.V. Milovanović, A.S. Cvetković and M.P. Stanić
ChristoffelDarboux Formula for Orthogonal Trigonometric Polynomials of SemiInteger Degree  S.S. Dragomir and M.S. Moslehian
Some Inequalities for ( ; )Normal Operators in Hilbert Spaces  V. Stojanović and B. Popović
Discrete Autoregressive Stopping Time Model  M. Acharya, B. P. Acharya and M. M. Nayak
Approximate Evaluation of Integrals of Analytic Functions  Author Index Volumes 1  23 (1986  2008)
Vol. 22, (2007)

Vol. 22, No 2 (2007)
 N. P. Cakić
On the Numbers Related to the Stirling Numbers of the Second Kind  S. S. Dragomir
New Reverses of the CauchyBunyakovskySchwarz Integral Inequality for VectorValued Functions in Hilbert Spaces and Applications  P. S. Milojević
Homeomorphisms and Finite Solvability of Their Perturbations for Fredholm Maps of Index Zero With Applications  G. Mastroianni and G.V. Milovanović
Polynomial Approximation on Unbounded Intervals by Fourier Sums  M. A. Kovačević
A Simple Algorithm for the Construction of Lagrange and Hermite Interpolating Polynomial in Two Variables  V. V. Vučković
The Method of the Chess Search Algorithms Parallelization Using TwoProcessor Distributed System  T. Sekulić and P. Hotomski
Influence of Norms on the Results of Query for Information Retrieval Mechanisms Based on Thesaurus
 N. P. Cakić

Vol. 22, No 1 (2007)
 K. Drakakis
A Note on the Appearance of Consecutive Numbers Amongst the Set of Winning Numbers in Lottery  I. D. Aranđelović and D. S. Petković
An Inequality for the Lebesgue Measure and its Applications  B. G. Pachpatte
New Discrete OstrowskiGrss Like Inequalities  H. Talibi Alaoui and R. Yafia
Supercritical Hopf Bifurcation in Delay Differential Equations  An Elementary Proof of Exchange of Stability  O. T. Pop
Approximation of Bcontinuous and Bdifferentiable Functions by GBS Operators Defined by Finite Sum  G. A. Anastassiou
Stochastic Korovkin Theory Given Quantitatively  S. S. Dragomir
Norm and Numerical Radius Inequalities for Sums of Bounded Linear Operators in Hilbert Spaces  G. V. Milovanović, A. S. Cvetković and M. P. Stanić
Two Conjectures for Integrals with Oscillatory Integrands  M. S. Petković, Lj. D. Petković and S. M. Ilić
On the Convergence of the Third Order RootSolver
 K. Drakakis
Vol. 21, (2006)
 Lj. M. Kocić and S. Spasić
Orthonormal Decomposition of Fractal Interpolating Functions  G. V. Milovanović, A. S. Cvetković, M. M. Matejić
Remark on Orthogonal Polynomials Induced by the Modified Chebyshev Measure of the Second Kind  I. Tascu
On the Approximation of Trivariate Functions by Means of Some TensorProduct Positive Linear Operators  S. S. Dragomir
Reverses of the Triangle Inequality Via Selberg's and BoasBellman's Inequalities  S. Karanasios and D. Pappas
Generalized Inverses and Special Type Operator Algebras  S. Simić
An Estimation of the Singular Values of Integral Operator with Logarithmic Kernel  B. Č. Popović and M. M. Ristić
Consistent Estimating in Uar Models  Lj. M. Kocić and M. M. Matejić
Contractive Affine Transformations of Complex Plane and Applications  M. S. Petković and L. Z. Rančić
On the Guaranteed Convergence of the ChebyshevLike Method for Computing Polynomial Zeros  E. I. Milovanović, M. P. Bekakos, I. Ž. Milovanović, T. Z. Mirković
Systolic Matrix Vector Iterations  M. Stanojević and S. Vraneš
Knowledge Representation for Natural Language Understanding  J. Karrakchou, M. Rachik and S. Gourari
Variation of Domains and Concept of Maximal Output Admissible Sets
Vol. 20, (2005)
 A. Ivić
Some Identities for the Riemann ZetaFunction II  J. A. Oguntuase and E. O. Adeleke
On Hardy's Integral Inequality  M. Akkouchi
On the Mapping H of S. S. Dragomir  I. Tascu
Approximation of Bivariate Functions by Operators of StancuHurwitz Type  G. V. Milovanović, A. S. Cvetković and M. P. Stanić
Multiple Orthogonal Polynomials on the Semicircle  P. M. Miličić
On the Best Approximation in Smooth and Uniformly Convex Real Banach Space  S. S. Dragomir
Refinements of Buzano's and Kurepa's Inequalities in Inner Product Spaces  P. S. Milojević
Some Generalizations of the First Fredholm Theorem to Hammerstein Equations and the Number of Solutions  Lj. Petrović and D.Stanojević
Some Models of Causality and Weak Solutions of Stochastic Differential Equations With Driving Semimartingales  Lj. Petrović and S. Dimitrijević
Some Models of Causality and Stochastic Differential Equation Driven by Fractional Brownian Motion  G. V. Milovanović, M. M. Spalević and M. S. Pranić
Maximum of the Modulus of Kernels in GaussTuran Quadratures With Chebyshev Weights: The Cases s = 1; 2  N. I. DjuranovićMiličić
On an Optimization Algorithm for LC^{1} Unconstrained Optimization  M. Stanković and S. Stojković
Reduction of Decision Diagrams by Disjunctive Spectral Translation in the WalshHadamard Domain
Vol. 19, (2004)
 Special Issue Dedicated to Professor Giuseppe Mastroianni
 S. S. Dragomir
Some Companions of Ostrowski's Inequality for Absolutely Continuous Functions and Applications  A. S. Cvetković and G. V. Milovanović
The Mathematica Package "OrthogonalPolynomials"  U. Abel and B. Della Vecchia
Enhanced Asymptotic Approximation by Linear Approximation Operators  O. Agratini and B. Della Vecchia
Mastroianni Operators Revisited  D. Barbosu
DurrmeyerSchurer Type Operators  J. Hernandez and F. Marcellan
An Extension of LeverrierFaddeev Algorithm Using a Basis of Classical Orthogonal Polynomials  P. Junghanns and K. Rost
Krylov Subspace Methods for Cauchy Singular Integral Equations  B. Silbermann
Asymptotic Invertibility of Continuous Functions of Onesided Invertible Operators  A. S. Cvetković and M. C. De Bonis
Projection Methods for Cauchy Singular Integral Equations on the Bounded Intervals
Vol. 18, (2003)
 B. S. Popov and H. M. Srivastava
LINEARIZATION OF A PRODUCT OF TWO POLYNOMIALS OF DIFFERENT ORTHOGONAL SYSTEMS  G. V. Milovanović and M. Stanić
CONSTRUCTION OF MULTIPLE ORTHOGONAL POLYNOMIALS BY DISCRETIZED STIELTJESGAUTSCHI PROCEDURE AND CORRESPONDING GAUSSIAN QUADRATURES  G. V. Milovanović and A. S. Cvetković
AN APPLICATION OF LITTLE 1/QJACOBI POLYNOMIALS TO SUMMATION OF CERTAIN SERIES  H. H. Khan and G. Ram
ON THE DEGREE OF APPROXIMATION  D. Stojanović and S. DjordevićKajan
MODELING MOBILE POINT OBJECTS IN LOCATIONBASED SERVICES
Vol. 17, (2002)
 D. Banković
All General Solutions of Prešić's Equation  M. Akkouchi
A Result on the Mapping H of S. S. Dragomir With Applications  M. J. Atia, F. Marcellán and I. A. Rocha
On Semiclassical Orthogonal Polynomials: A QuasiDefinite Functional of Class 1  A. Jeribi
On the Schechter Essential Spectrum on Banach Spaces and Application  G. V. Milovanovic and A. S. Cvetkovic
Numerical Integration of Functions With Logarithmic End Point Singularity  M. L. Manwaring and V. D. Malbaša
An Architecture for Parallel Interpretation of Abstract Machine Languages  L. Stoimenov and S. ĐorđevicKajan
Framework for Semantic GIS Interoperability
Vol. 16, (2001)
 S. Marinković, M. Rašković, R.D Đorđević
Weak Probability Polyadic Algebras  M. Merkle
Conditions for Convexity of a Derivative and Applications to the Gamma and Digamma Function  B.G. Pachpatte
An Inequality of Ostrowski Type in n Independent Variables  J.A. Oguntuase
GronwallBellman Type Integral Inequalities for Multidistributions  B.G. Pachpatte
Inequalities Relate to the Zeros of Solutions of Certain Second Or er Differential Equations  M. Tomić
The Converse Theorem of Approximation by Angle in Various Metrics for Nonperiodic Functions  D. Hajduković
Some Problems of Convergence in Norme Spaces  Lj. Gajić
Maximal elements and equilibria for U majorise preferences in not Necessarily Locally Convex Topological Vector Spaces  P.S. Milojević
On the Number of Solutions of Nonlinear Equations  U.C. De and J. Sengupta
On a Type of SemiSymmetric Metric Connection on an Almost Contact Metric Manifold  Z. Obradović and R. Srikumar
Parallelizing Design of Application Tailore Neural Networks
Vol. 15, (2000)
 P.S. Stanimirović
gInverses and Canonical Forms  J.A. Oguntuase
On Weighted Norm Inequalities for Operators of Hardy Type  I. Jovanović
Multipliers from H^{1}(U) into BMOA(B)  B.D. Crstici and N.N. Neamtu
On the LogQuadratic Functional Equation  Lj. M. Kocić and A.C. Simoncelli
Functional Equations for Fractal Interpolants  M. Tomić
On Converse Theorem of Approximation in Various Metrics for Periodic Functions of Several Variables  A. Bejancu
Coisotropic Submanifolds of PseudoFinsler Manifolds  G.V. Milovanović and A.S. Cvetković
Note on a Construction of Weights in GaussType Quadrature Rule  M.S. Petković and D.V. Vranić
On the Guaranteed Convergence of a Family of Simultaneous Iterative Methods  B.M. Ranđelović, L.V. Stefanović and B.M. Danković
Numerical Solution of Impulsive Differential Equations  B.S. Jovanović and D. Bojović
Finite Difference Method for the Heat Equation With Coefficient From Anisotropic Sobolev Space  I.Ž. Milovanović, T.I. Tokić, E.I. Milovanović, M.K. Stojčev
Determining the Number of Processing Elements in Systolic Arrays  Z. Obradović and R. Srikumar
Constructive Neural Networks Design Using Genetic Optimization  D.Č. Stefanović, I.D. Stefanović and D.R. Blagojević
The Envelope of Compositions Curves
Vol. 14, (1999)
 B. Dragović
On Some Finite Sums with Factorials  A. Stokolos
On the Rate of Approximation Almost Everywhere by Steklov Means With Respect to Multidimensional Intervals  M. Pikula and T. Marjanović
The Regulation Independent of the Potential Symmetrical to the Center for Sturm'Liouville Operator With a Constant Delay  J. Popenda and E. Schmeidel
Asymptotically Periodic Solution of Some Linear Difference Equations  O. Agratini
On a Sequence of Linear and Positive Operators  W. Themistoclakis
Trigonometric Wavelet Interpolation in Besov Spaces  A. Torgašev
Dual Space of a Quaternion Hilbert Space  V. Rakočević
Apostol Spectrum and Generalizations: a Brief Survey  M. C. De Bonis
An Algorithm for the Evaluation of the TwoDimensional Hilbert Transform With Nonstandard Weight Functions  P. P. Blaga
An Approximate Formula for Multiple Integrals  N. Kjurkchiev and M. S. Petković
On the Divergent Properties of Twosided SOR Weierstrass Method  S. V. Pereverzev
On the Sparse Representation of Operators for Solving IllPosed Problems  S. G. Solodky
Complexity for Some Classes of Equations of the Second Kind
Vol. 13, (1998)
 Z. Marković
Intuitionistic and Classical Satisfability in Kripke Models  Ž. Mijajlović and Z. Marković
Some Recurrence Formulas to the Differential Operator θD  V. Yu. Protasov
Generalisation of the Joint Spectral Radius: The Geometrical Approach  G. B. Đorđević
Polynomials Related to Gegenbauer Polynomials  S. Pilipović and M. Stojanović
Generalized Goursat Problem and the Quasiasymptotics of a Solution  A. Tali
On Convex Families of Summability Methods  Lj. M. Kocić and B. Della Vecchia
Degeneracy of Positive Linear Operators  Y. L. Nosenko
Approximation of the Function by Fourier Series  E. Bairamov and A. O. Celebi
Spectral Analysis of Nonselfadjoint Schrodinger Operators With Spectral Parameter in Boundary Conditions  D. M. Milošević and Lj. M. Kocić
Fractal Surfaces Leveling  S. Janković and M. Jovanović
A General Algorithm for Solving Stochastic Hereditary Integrodifferential Equations  M. R. Capobianco and N. Mastronardi
A Numerical Method for a Volterratype Integral Equations With Logarithmic Kernel  K. Stevanović Hedrih
Derivatives of the Mass Moment Vectors at the Dimensional Coordinate System N  V. Stojanović, S. Radovanović and J. Bogdanović
Least Squres Approximation of Multiport Network Parameters by Rational Functions