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Opfer, Gerhard

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Author ID: opfer.gerhard Recent zbMATH articles by "Opfer, Gerhard"
Published as: Opfer, G.; Opfer, Gerhard
Documents Indexed: 86 Publications since 1968, including 6 Books
Reviewing Activity: 34 Reviews
Biographic References: 1 Publication

Publications by Year

Citations contained in zbMATH Open

51 Publications have been cited 269 times in 176 Documents Cited by Year
Richardson’s iteration for nonsymmetric matrices. Zbl 0565.65012
Opfer, Gerhard; Schober, Glenn
27
1984
A note on the computation of all zeros of simple quaternionic polynomials. Zbl 1247.65060
Janovská, Drahoslava; Opfer, Gerhard
21
2010
The derivation of cubic splines with obstacles by methods of optimization and optimal control. Zbl 0628.41012
Opfer, Gerhard; Oberle, Hans Joachim
21
1988
Chebyshev-Vandermonde systems. Zbl 0755.65032
Reichel, Lothar; Opfer, Gerhard
18
1991
Polynomials and Vandermonde matrices over the field of quaternions. Zbl 1196.11154
Opfer, Gerhard
13
2009
Linear equations in quaternionic variables. Zbl 1179.11042
Janovská, Drahoslava; Opfer, Gerhard
12
2008
The classification and the computation of the zeros of quaternionic, two-sided polynomials. Zbl 1190.65075
Janovská, Drahoslava; Opfer, Gerhard
11
2010
Complex Chebyshev polynomials on circular sectors with degree six or less. Zbl 0496.65002
Grothkopf, U.; Opfer, G.
10
1982
Complex planar splines. Zbl 0462.41010
Opfer, Gerhard
8
1981
Zeros and singular points for one-sided coquaternionic polynomials with an extension to other \(R^4\) algebras. Zbl 1307.65060
Janovská, Drahoslava; Opfer, Gerhard
7
2014
Computing quaternionic roots by Newton’s method. Zbl 1160.65016
Janovská, Drahoslava; Opfer, Gerhard
7
2007
Explicit Faber polynomials on circular sectors. Zbl 0751.30003
Gatermann, Karin; Hoffmann, Christoph; Opfer, Gerhard
7
1992
New extremal properties for constructing conformal mappings. Zbl 0432.30007
Opfer, Gerhard
7
1979
An algorithm for the construction of best approximations based on Kolmogorov’s criterion. Zbl 0417.41012
Opfer, Gerhard
7
1978
A local algorithm for constructing non-negative cubic splines. Zbl 0731.41016
Fischer, Bernd; Opfer, Gerhard; Puri, Madan L.
6
1991
Eiene Methode zur Lösung des komplexen Approximationsproblems mit einer Anwendung auf konforme Abbildungen. Zbl 0302.65008
Krabs, W.; Opfer, G.
6
1975
Linear equations and the Kronecker product in coquaternions. Zbl 1298.15006
Janovská, Drahoslava; Opfer, Gerhard
5
2013
Givens’ transformation applied to quaternion valued vectors. Zbl 1052.65030
Janovská, D.; Opfer, G.
5
2003
Supplement to: Explicit Faber polynomials on circular sectors. Zbl 0751.30004
Gatermann, Karin; Hoffmann, Christoph; Opfer, Gerhard
5
1992
On monotonicity preserving linear extrapolation sequences. Zbl 0199.50101
Opfer, G.
5
1970
Die Bestimmung des Moduls zweifach zusammenhängender Gebiete mit Hilfe von Differenzenverfahren. Zbl 0187.40302
Opfer, G.
5
1969
On the construction of optimal monotone cubic spline interpolations. Zbl 0934.41009
Fredenhagen, Sigrid; Oberle, Hans Joachim; Opfer, Gerhard
4
1999
Solving complex approximation problems by semiinfinite-finite optimization techniques: A study on convergence. Zbl 0517.65005
Opfer, Gerhard
4
1982
Conformal mappings onto prescribed regions via optimization techniques. Zbl 0417.30012
Opfer, Gerhard
4
1980
Complex Chebyshev polynomials on circular sectors. Zbl 0393.41010
Geiger, Carl; Opfer, Gerhard
4
1978
The number of zeros of unilateral polynomials over coquaternions and related algebras. Zbl 1368.65069
Janovská, Drahoslava; Opfer, Gerhard
3
2017
Complex version of Catalan’s problem. Zbl 1007.11014
Opfer, Gerhard; Ripken, Wolfgang
3
1998
Nonnegative splines, in particular of degree five. Zbl 0910.65003
Oberle, H. J.; Opfer, G.
3
1998
On convergence and quasiregularity of interpolating complex planar splines. Zbl 0478.30030
Opfer, Gerhard; Schober, Glenn
3
1982
Matrices over nondivision algebras without eigenvalues. Zbl 1351.15014
Janovská, Drahoslava; Opfer, Gerhard
2
2016
The algebraic Riccati equation for quaternions. Zbl 1314.15012
Janovská, Drahoslava; Opfer, Gerhard
2
2013
Uniform approximation as a numerical tool for constructing conformal maps. Zbl 0587.30008
Hartmann, M.; Opfer, G.
2
1986
Anwendung komplexer Approximation auf die Lösung linearer Gleichungssysteme mit der Richardson-Iteration. Zbl 0531.65016
Opfer, G.
2
1983
Computation of T-approximations by complex planar splines. Zbl 0537.65023
Opfer, G.
2
1982
Konforme Abbildungen und ihre numerische Behandlung. Zbl 0305.30011
Opfer, Gerhard
2
1974
The relation between the companion matrix and the companion polynomial in \(\mathbb {R}^4\) algebras. Zbl 1431.15016
Janovská, Drahoslava; Opfer, Gerhard
1
2018
Niven’s algorithm applied to the roots of the companion polynomial over \(\mathbb {R}^4\) algebras. Zbl 1412.16016
Opfer, Gerhard
1
2017
Erratum to: “The Jacobi matrix for functions in noncommutative algebras”. Zbl 1336.65071
Lauterbach, Reiner; Opfer, Gerhard
1
2014
The Jacobi matrix for functions in noncommutative algebras. Zbl 1316.65049
Lauterbach, Reiner; Opfer, Gerhard
1
2014
Zero points of quadratic matrix polynomials. Zbl 1340.65080
Opfer, Gerhard; Janovská, Drahoslava
1
2013
An analytic approach to the Collatz \(3n+1\) problem for negative start values. Zbl 1329.11011
Berg, Lothar; Opfer, Gerhard
1
2013
The nonexistence of pseudoquaternions in \({\mathbb{C}^{2\times 2}}\). Zbl 1252.12002
Janovská, Drahoslava; Opfer, Gerhard
1
2011
Linear equations in quaternions. Zbl 1119.65328
Janovská, Drahoslava; Opfer, Gerhard
1
2006
Fast Givens transformation for quaternion valued matrices applied to Hessenberg reductions. Zbl 1078.65033
Janovská, Drahoslava; Opfer, Gerhard
1
2005
Complex Haar spaces generated by shifts applied to a single function. Zbl 1061.41019
Hengartner, Walter; Opfer, Gerhard
1
2002
Applications and computation of orthogonal polynomials. Conference at the Mathematical Research Institute Oberwolfach, Germany, March 22–29, 1998. Dedicated to the memory of Günther Hämmerlin. Zbl 0919.00065
Gautschi, W. (ed.); Golub, G. H. (ed.); Opfer, G. (ed.)
1
1999
Splines with prescribed modified moments. Zbl 0819.41011
Oberle, Hans Joachim; Opfer, Gerhard
1
1994
Numerische Behandlung komplexer Approximationsaufgaben. (Numerical treatment of complex approximation problems). Zbl 0701.65049
Opfer, Gerhard
1
1989
An algorithm for complex polynomial approximation with nonlinear constraints. Zbl 0611.65008
Mason, J. C.; Opfer, G.
1
1986
Numerical integration of weakly singular functions. Zbl 0452.65011
Anselone, P. M.; Opfer, G.
1
1979
Über die Approximation der Identität im Komplexen. Zbl 0306.30012
Opfer, G.
1
1975
The relation between the companion matrix and the companion polynomial in \(\mathbb {R}^4\) algebras. Zbl 1431.15016
Janovská, Drahoslava; Opfer, Gerhard
1
2018
The number of zeros of unilateral polynomials over coquaternions and related algebras. Zbl 1368.65069
Janovská, Drahoslava; Opfer, Gerhard
3
2017
Niven’s algorithm applied to the roots of the companion polynomial over \(\mathbb {R}^4\) algebras. Zbl 1412.16016
Opfer, Gerhard
1
2017
Matrices over nondivision algebras without eigenvalues. Zbl 1351.15014
Janovská, Drahoslava; Opfer, Gerhard
2
2016
Zeros and singular points for one-sided coquaternionic polynomials with an extension to other \(R^4\) algebras. Zbl 1307.65060
Janovská, Drahoslava; Opfer, Gerhard
7
2014
Erratum to: “The Jacobi matrix for functions in noncommutative algebras”. Zbl 1336.65071
Lauterbach, Reiner; Opfer, Gerhard
1
2014
The Jacobi matrix for functions in noncommutative algebras. Zbl 1316.65049
Lauterbach, Reiner; Opfer, Gerhard
1
2014
Linear equations and the Kronecker product in coquaternions. Zbl 1298.15006
Janovská, Drahoslava; Opfer, Gerhard
5
2013
The algebraic Riccati equation for quaternions. Zbl 1314.15012
Janovská, Drahoslava; Opfer, Gerhard
2
2013
Zero points of quadratic matrix polynomials. Zbl 1340.65080
Opfer, Gerhard; Janovská, Drahoslava
1
2013
An analytic approach to the Collatz \(3n+1\) problem for negative start values. Zbl 1329.11011
Berg, Lothar; Opfer, Gerhard
1
2013
The nonexistence of pseudoquaternions in \({\mathbb{C}^{2\times 2}}\). Zbl 1252.12002
Janovská, Drahoslava; Opfer, Gerhard
1
2011
A note on the computation of all zeros of simple quaternionic polynomials. Zbl 1247.65060
Janovská, Drahoslava; Opfer, Gerhard
21
2010
The classification and the computation of the zeros of quaternionic, two-sided polynomials. Zbl 1190.65075
Janovská, Drahoslava; Opfer, Gerhard
11
2010
Polynomials and Vandermonde matrices over the field of quaternions. Zbl 1196.11154
Opfer, Gerhard
13
2009
Linear equations in quaternionic variables. Zbl 1179.11042
Janovská, Drahoslava; Opfer, Gerhard
12
2008
Computing quaternionic roots by Newton’s method. Zbl 1160.65016
Janovská, Drahoslava; Opfer, Gerhard
7
2007
Linear equations in quaternions. Zbl 1119.65328
Janovská, Drahoslava; Opfer, Gerhard
1
2006
Fast Givens transformation for quaternion valued matrices applied to Hessenberg reductions. Zbl 1078.65033
Janovská, Drahoslava; Opfer, Gerhard
1
2005
Givens’ transformation applied to quaternion valued vectors. Zbl 1052.65030
Janovská, D.; Opfer, G.
5
2003
Complex Haar spaces generated by shifts applied to a single function. Zbl 1061.41019
Hengartner, Walter; Opfer, Gerhard
1
2002
On the construction of optimal monotone cubic spline interpolations. Zbl 0934.41009
Fredenhagen, Sigrid; Oberle, Hans Joachim; Opfer, Gerhard
4
1999
Applications and computation of orthogonal polynomials. Conference at the Mathematical Research Institute Oberwolfach, Germany, March 22–29, 1998. Dedicated to the memory of Günther Hämmerlin. Zbl 0919.00065
Gautschi, W. (ed.); Golub, G. H. (ed.); Opfer, G. (ed.)
1
1999
Complex version of Catalan’s problem. Zbl 1007.11014
Opfer, Gerhard; Ripken, Wolfgang
3
1998
Nonnegative splines, in particular of degree five. Zbl 0910.65003
Oberle, H. J.; Opfer, G.
3
1998
Splines with prescribed modified moments. Zbl 0819.41011
Oberle, Hans Joachim; Opfer, Gerhard
1
1994
Explicit Faber polynomials on circular sectors. Zbl 0751.30003
Gatermann, Karin; Hoffmann, Christoph; Opfer, Gerhard
7
1992
Supplement to: Explicit Faber polynomials on circular sectors. Zbl 0751.30004
Gatermann, Karin; Hoffmann, Christoph; Opfer, Gerhard
5
1992
Chebyshev-Vandermonde systems. Zbl 0755.65032
Reichel, Lothar; Opfer, Gerhard
18
1991
A local algorithm for constructing non-negative cubic splines. Zbl 0731.41016
Fischer, Bernd; Opfer, Gerhard; Puri, Madan L.
6
1991
Numerische Behandlung komplexer Approximationsaufgaben. (Numerical treatment of complex approximation problems). Zbl 0701.65049
Opfer, Gerhard
1
1989
The derivation of cubic splines with obstacles by methods of optimization and optimal control. Zbl 0628.41012
Opfer, Gerhard; Oberle, Hans Joachim
21
1988
Uniform approximation as a numerical tool for constructing conformal maps. Zbl 0587.30008
Hartmann, M.; Opfer, G.
2
1986
An algorithm for complex polynomial approximation with nonlinear constraints. Zbl 0611.65008
Mason, J. C.; Opfer, G.
1
1986
Richardson’s iteration for nonsymmetric matrices. Zbl 0565.65012
Opfer, Gerhard; Schober, Glenn
27
1984
Anwendung komplexer Approximation auf die Lösung linearer Gleichungssysteme mit der Richardson-Iteration. Zbl 0531.65016
Opfer, G.
2
1983
Complex Chebyshev polynomials on circular sectors with degree six or less. Zbl 0496.65002
Grothkopf, U.; Opfer, G.
10
1982
Solving complex approximation problems by semiinfinite-finite optimization techniques: A study on convergence. Zbl 0517.65005
Opfer, Gerhard
4
1982
On convergence and quasiregularity of interpolating complex planar splines. Zbl 0478.30030
Opfer, Gerhard; Schober, Glenn
3
1982
Computation of T-approximations by complex planar splines. Zbl 0537.65023
Opfer, G.
2
1982
Complex planar splines. Zbl 0462.41010
Opfer, Gerhard
8
1981
Conformal mappings onto prescribed regions via optimization techniques. Zbl 0417.30012
Opfer, Gerhard
4
1980
New extremal properties for constructing conformal mappings. Zbl 0432.30007
Opfer, Gerhard
7
1979
Numerical integration of weakly singular functions. Zbl 0452.65011
Anselone, P. M.; Opfer, G.
1
1979
An algorithm for the construction of best approximations based on Kolmogorov’s criterion. Zbl 0417.41012
Opfer, Gerhard
7
1978
Complex Chebyshev polynomials on circular sectors. Zbl 0393.41010
Geiger, Carl; Opfer, Gerhard
4
1978
Eiene Methode zur Lösung des komplexen Approximationsproblems mit einer Anwendung auf konforme Abbildungen. Zbl 0302.65008
Krabs, W.; Opfer, G.
6
1975
Über die Approximation der Identität im Komplexen. Zbl 0306.30012
Opfer, G.
1
1975
Konforme Abbildungen und ihre numerische Behandlung. Zbl 0305.30011
Opfer, Gerhard
2
1974
On monotonicity preserving linear extrapolation sequences. Zbl 0199.50101
Opfer, G.
5
1970
Die Bestimmung des Moduls zweifach zusammenhängender Gebiete mit Hilfe von Differenzenverfahren. Zbl 0187.40302
Opfer, G.
5
1969
all top 5

Cited by 246 Authors

26 Opfer, Gerhard
7 Reichel, Lothar
6 Hadjidimos, Apostolos
6 Janovská, Drahoslava
6 Olshevsky, Vadim
5 Schmidt, Jochen Wilhelm
4 Fischer, Bernd
4 Kailath, Thomas
3 Ali, Istkhar
3 Dikshit, Hanuman Prasad
3 Nowak, Werner Georg
3 Ojha, Aparajita
3 Ong, Boon-Hua
3 Ruscheweyh, Stephan
3 Zhang, Jun
2 Bella, Tom
2 Bolotnikov, Vladimir
2 Boros, Tibor
2 Calvetti, Daniela
2 Chapman, Adam
2 Coleman, John P.
2 Córdova, Antonio
2 Dospra, Petroula
2 Eidelman, Yuli
2 Eiermann, Michael
2 Falcão, Maria Irene
2 Farouki, Rida T.
2 Feng, Lianggui
2 Freund, Roland W.
2 Galanis, Sofoklis
2 Gallopoulos, Efstratios
2 Gatermann, Karin
2 Gautschi, Walter
2 Gohberg, Israel
2 He, Matthew Xisheng
2 Hengartner, Walter
2 Hoffmann, Christoph M.
2 Jia, Zhigang
2 Kaya, C. Yalçin
2 Lauterbach, Reiner
2 Le Bihan, Nicolas
2 Macias-Virgós, Enrique
2 Mierzejewski, Dmytro A.
2 Niethammer, Wilhelm
2 Pereira-Sáez, María José
2 Puri, Madan Lal
2 Safique Ahmad, Sk.
2 Sakkalis, Takis
2 Saylor, Paul E.
2 Schober, Glenn Edward
2 Schoißengeier, Johannes
2 Shpakivskyi, Vitalii Stanislavovich
2 Smolarski, Dennis C.
2 Stoppato, Caterina
2 Tzoumas, Michael G.
2 Varga, Richard Steven
2 Zhao, Meixiang
1 Abdulhadi, Zayid
1 Abdullayev, Fahreddin G.
1 Adsuara, J. E.
1 Ali, Iskander
1 Ali, Rosihan Mohamed
1 Allen, Larry
1 Aloy, Miguel-Ángel
1 Altavilla, Ademeo
1 Andersson, Lars-Erik
1 Bastian-Walther, Marion
1 Bell, Jason P.
1 Belward, John Alan
1 Belyj, V. I.
1 Ben Romdhane, Neila
1 Blatt, Hans-Peter
1 Blu, Thierry
1 Bogdanov, Vladimir V.
1 Brezinski, Claude
1 Bruhn, Andrés
1 Bshouty, Daoud H.
1 Burbea, Jacob
1 Burić, Ilija
1 Cahueñas, Oskar
1 Cerdá-Durán, Pablo
1 Chan, Eng Seong
1 Chen, Meiqin
1 Chen, Yong
1 Cheng, Dong
1 Cheng, Lizhi
1 Cheng, Wei
1 Cheng, Xuehan
1 Chiu, Chichia
1 Cordero-Carrión, Isabel
1 Corless, Robert Malcolm
1 de Fabritiis, Corrado
1 de Hoop, Maarten V.
1 de Pillis, John
1 Demanet, Laurent
1 Dontchev, Asen L.
1 Egecioglu, Omer
1 Elfving, Tommy
1 Ellacott, Stephen W.
1 Erdoğdu, Melek
...and 146 more Authors
all top 5

Cited in 61 Serials

17 Numerische Mathematik
17 Linear Algebra and its Applications
17 Advances in Applied Clifford Algebras
15 Journal of Computational and Applied Mathematics
9 Mathematics of Computation
9 Journal of Approximation Theory
6 BIT
6 Computing
5 Computers & Mathematics with Applications
4 Linear and Multilinear Algebra
4 Numerical Algorithms
3 Computer Aided Geometric Design
3 Journal of Symbolic Computation
2 Applicable Analysis
2 Mathematical Proceedings of the Cambridge Philosophical Society
2 Ukrainian Mathematical Journal
2 Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg
2 Applied Mathematics and Computation
2 Theoretical Computer Science
2 Applied Numerical Mathematics
2 SIAM Journal on Matrix Analysis and Applications
2 Computational Optimization and Applications
2 Abstract and Applied Analysis
2 Computational Methods and Function Theory
1 Journal of Computational Physics
1 Journal of Mathematical Analysis and Applications
1 Journal of Statistical Physics
1 Mathematical Notes
1 Acta Arithmetica
1 Integral Equations and Operator Theory
1 Journal of Algebra
1 Journal of Optimization Theory and Applications
1 Mathematische Zeitschrift
1 Transactions of the American Mathematical Society
1 SIAM Journal on Algebraic and Discrete Methods
1 Journal of Complexity
1 Constructive Approximation
1 Applied Mathematics Letters
1 Mathematical and Computer Modelling
1 Journal of Scientific Computing
1 Signal Processing
1 Aequationes Mathematicae
1 Journal of Computer and Systems Sciences International
1 SIAM Journal on Scientific Computing
1 Journal de Théorie des Nombres de Bordeaux
1 Applied and Computational Harmonic Analysis
1 International Journal of Computer Vision
1 ETNA. Electronic Transactions on Numerical Analysis
1 Advances in Computational Mathematics
1 Integral Transforms and Special Functions
1 Journal of High Energy Physics
1 Journal of Zhejiang University. Science
1 Foundations of Computational Mathematics
1 Comptes Rendus. Mathématique. Académie des Sciences, Paris
1 Journal of Algebra and its Applications
1 Kodai Mathematical Seminar Reports
1 Complex Variables and Elliptic Equations
1 The Annals of Applied Statistics
1 Analysis and Mathematical Physics
1 Journal of Applied Analysis and Computation
1 Bulletin of Computational Applied Mathematics

Citations by Year