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Janne Heittokangas

Janne Heittokangas

University Lecturer

Department of Physics and Mathematics, Faculty of Science, Forestry and Technology

[email protected] | +358 50 442 2381

Information Publications

Research groups

Complex Analysis 30.08.2018 -

Publications

61/61 items

Convergence of sub-series' and sub-signed series' in terms of the asymptotic ψ-density
Heittokangas, Janne; Latreuch, Zinelaabidine. 2025. Bulletin des sciences mathematiques. 204: . 103683 A1 Journal article (refereed), original research
Standard solutions of complex linear differential equations
Heittokangas, Janne; Pulkkinen, Samu; Yu, Hui; Zemirni, Mohamed Amine. 2024. Annales Fennici mathematici. 49: 663-683 A1 Journal article (refereed), original research
A Continuous Transition from E-Sets to R-sets and Beyond
Ding, Jie; Heittokangas, Janne; Wen, Zhi-Tao. 2023. Journal of geometric analysis. 33: . 278 A1 Journal article (refereed), original research
Asymptotic integration theory for f''+ P(z)f=0
Gundersen, Gary G.; Heittokangas, Janne; Zemirni, Mohamed Amine. 2022. Expositiones mathematicae. 40: 94-126 A1 Journal article (refereed), original research
Description of growth and oscillation of solutions of complex LDE’s
Chyzhykov, Igor; Gröhn, Janne; Heittokangas, Janne; Rättyä, Jouni. 2022. Journal of the australian mathematical society. [Published online 16 June 2022]: 1-27 A1 Journal article (refereed), original research
Irregular finite order solutions of complex LDE's in unit disc
Chyzhykov, Igor; Filevych, Petro; Gröhn, Janne; Heittokangas, Janne; Rättyä, Jouni. 2022. Journal de mathematiques pures et appliquees. 160: 158-201 A1 Journal article (refereed), original research
Meromorphic Functions of Finite ϕ-order and Linear Askey—Wilson Divided Difference Equations
Yu, Hui; Heittokangas, Janne; Wang, Jun; Wen, Zhi Tao. 2022. Acta mathematica sinica : english series. 38: 371-383 A1 Journal article (refereed), original research
Opiskelun joustavuuden lisääminen matematiikan yliopisto-opintojen taitekohdassa
Eronen Lasse; Heittokangas Janne. 2022. FMSERA Journal. 5: 61-75 A1 Journal article (refereed), original research
Oscillation of Solutions of LDE’s in Domains Conformally Equivalent to Unit Disc
Chyzhykov, I.; Gröhn, J.; Heittokangas, J.; Rättyä, J.. 2022. Journal of geometric analysis. 32: A1 Journal article (refereed), original research
Value distribution of exponential polynomials and their role in the theories of complex differential equations and oscillation theory
Heittokangas, Janne; Ishizaki, Katsuya; Tohge, Kazuya; Wen, Zhi‐Tao. 2022. Bulletin of the london mathematical society. 2023; 55: 1-77 A2 Review article, Literature review, Systematic review
Contour integral solutions of linear differential equations which include a generalization of the Airy integral
Gundersen, Gary G; Heittokangas, Janne M; Wen, Zhi-Tao. 2021. Houston journal of mathematics. 47: 321–351 A1 Journal article (refereed), original research
Dual exponential polynomials and a problem of Ozawa
Heittokangas, Janne; Ishizaki, Katsuya; Tohge, Kazuya; Wen, Zhi-Tao. 2021. Proceedings of the Royal Society of Edinburgh section A: mathematics. 152: 701-719 A1 Journal article (refereed), original research
Meromorphic functions of finite φ-order and linear q-difference equations
Heittokangas, J; Wang, J; Wen, ZT; Yu, H. 2021. Journal of difference equations and applications. 27: 1280-1309 A1 Journal article (refereed), original research
On Petrenko's deviations and second order differential equations
Heittokangas, Janne; Zemirni, Mohamed Amine. 2021. Kodai mathematical journal. 44: 181-193 A1 Journal article (refereed), original research
On meromorphic solutions of non-linear differential equations of Tumura - Clunie type
Heittokangas, J; Latreuch, Z; Wang, J; Zemirni, M A. 2021. Mathematische nachrichten. 294: 748-773 A1 Journal article (refereed), original research
On the limits of real-valued functions in sets involving Ψ-density, and applications
Heittokangas, Janne; Latreuch, Zinelaabidine; Wang, Jun; Zemirni, Amine. 2021. Journal of mathematical analysis and applications. 507: 125787 A1 Journal article (refereed), original research
The asymptotic number of zeros of exponential sums in critical strips
Heittokangas, J; Wen, ZT. 2021. Monatshefte fur mathematik. 194: 261-273 A1 Journal article (refereed), original research
Deficient Values of Solutions of Linear Differential Equations
Gundersen, Gary G; Heittokangas, Janne; Wen, Zhi-Tao. 2020. Computational methods and function theory. 2021; 21: 145-177 A1 Journal article (refereed), original research
Exponential polynomials in the oscillation theory
Heittokangas, Janne; Ishizaki, Katsuya; Laine, Ilpo; Tohge, Kazuya. 2020. Journal of differential equations. 272: 911-937 A1 Journal article (refereed), original research
Generalization of Pólya's Zero Distribution Theory for Exponential Polynomials, and Sharp Results for Asymptotic Growth
Heittokangas, Janne; Wen, Zhi-Tao. 2020. Computational methods and function theory. 2021; 21: 245-270 A1 Journal article (refereed), original research
On the number of linearly independent admissible solutions to linear differential and linear difference equations
Heittokangas, Janne; Yu, Hui; Zemirni, Mohamed Amine. 2020. Canadian journal of mathematics-journal canadien de mathematiques. 2021; 73: 1556-1591 A1 Journal article (refereed), original research
Complex oscillation and nonoscillation results
Heittokangas, Janne; Ishizaki, Katsuya; Laine, Ilpo; Tohge, Kazuya. 2019. Transactions of the american mathematical society. 372: 6161-6182 A1 Journal article (refereed), original research
Zero distribution and division results for exponential polynomials
Heittokangas, Janne; Ishizaki, Katsuya; Tohge, Kazuya; Wen, Zhi-Tao. 2018. Israel journal of mathematics. 227: 397-421 A1 Journal article (refereed), original research
Dual exponential polynomials and linear differential equations
Wen Zhi-Tao, Gundersen Gary G, Heittokangas Janne. 2017. Journal of differential equations. 2018; 264: 98-114 A1 Journal article (refereed), original research
On the relationship between the lower order of coefficients and the growth of solutions of differential equations
Long Jianren, Heittokangas Janne, Ye Zhuan. 2016. Journal of mathematical analysis and applications. 444: 153-166 A1 Journal article (refereed), original research
Completely regular growth solutions of second order complex linear differential equations
Heittokangas Janne, Laine Ilpo, Tohge Kazuya, Wen Zhi-Tao. 2015. Annales academiae scientiarum fennicae-mathematica. 40: 985-1003 A1 Journal article (refereed), original research
Second-order complex linear differential equations with special functions or extremal functions as coefficients
Wu Xiubi, Long Jianren, Heittokangas Janne, Qiu Ke-e. 2015. Electronic journal of differential equations. 2015: 1-15 A1 Journal article (refereed), original research
Functions of finite logarithmic order in the unit disc, Part I
Heittokangas Janne, Wen Zhi-Tao. 2014. Journal of mathematical analysis and applications. 415: 435-461 A1 Journal article (refereed), original research
Functions of finite logarithmic order in the unit disc, Part II
Heittokangas Janne, Wen Zhi-Tao. 2014. Computational methods and function theory. -: 1-22 A1 Journal article (refereed), original research
On alpha-Polynomial Regular Functions, with Applications to Ordinary Differential Equations
Fenton Peter, Gröhn Janne, Heittokangas Janne, Rossi John, Rättyä Jouni. 2014. Proceedings of the Edinburgh Mathematical Society. 57: 405-421 A1 Journal article (refereed), original research
On the complexity of finding a necessary and sufficient condition for Blaschke-oscillatory equations
Heittokangas Janne, Reijonen Atte. 2014. Glasgow mathematical journal. -: 1-12 A1 Journal article (refereed), original research
Zero separation results for solutions of second order linear differential equations
Chuaqui Martin, Gröhn Janne, Heittokangas Janne, Rättyä Jouni. 2013. Advances in mathematics. 245: 382-422 A1 Journal article (refereed), original research
Blaschke Products and Their Applications
Grudsky Sergei, Shargorodsky Eugene, Gauthier Paul, Heittokangas Janne, Boivin Andre, Zhu Changzhong, Mashreghi Javad, Cima Joseph, Pfaltzgraff John, Kraus Daniela, Roth Oliver, Chyzhykov Igor, Skaskiv Severyn, Gluchoff Alan, Hartmann Frederick, Baribeau Line, Feichtinger Hans, Pap Margit, Martin Maria, Vukotic Dragan et al.. Teoksessa: Javad Mashreghi, Emmanuel Fricain(toim.) , 2012. A survey on Blaschke-oscillatory differential.... s. 43-98. Springer A3 Book section, Chapters in research books
Exponential polynomials as solutions of certain nonlinear difference equations
Wen Zhi Tao, Heittokangas Janne, Laine Ilpo. 2012. Acta mathematica sinica : english series. 28: 1295-1306 A1 Journal article (refereed), original research
New Findings on the Bank-Sauer Approach in Oscillation Theory
Gröhn Janne, Heittokangas Janne. 2012. Constructive approximation. 35: 345-361 A1 Journal article (refereed), original research
A unit disc analogue of the Bank-Laine conjecture does not hold
Heittokangas Janne, Tohge Kazuya. 2011. Annales academiae scientiarum fennicae-mathematica. 36: 341-351 A1 Journal article (refereed), original research
On interpolating Blaschke products and Blaschke-oscillatory equations
Heittokangas Janne. 2011. Constructive approximation. 34: 1-21 A1 Journal article (refereed), original research
Possible Intervals for T- and M-Orders of Solutions of Linear Differential Equations in the Unit Disc
Chuaqui Martin, Gröhn Janne, Heittokangas Janne, Rättyä Jouni. 2011. Abstract and applied analysis. 2011: - A1 Journal article (refereed), original research
Uniqueness of meromorphic functions sharing values with their shifts
Heittokangas J, Korhonen R, Laine I, Rieppo J. 2011. Complex variables and elliptic equations. 56: 81-92 A1 Journal article (refereed), original research
Zero distribution of solutions of complex linear differential equations determines growth of solutions
Heittokangas Janne, Rättyä Jouni. 2011. Mathematische nachrichten. 284: 412-420 A1 Journal article (refereed), original research
Sharp logarithmic derivative estimates with applications to ordinary differential equations in the unit disc
I. Chyzhykov, J. Heittokangas, J. Rättyä. 2010. Journal of the australian mathematical society. 88: 145-167 A1 Journal article (refereed), original research
Finiteness of &phi: order of solutions of linear differential equations in the unit disc
I. Chyzhykov, J. Heittokangas, J. Rättyä. 2009. Journal d'analyse mathématique. 109: 163-198 A1 Journal article (refereed), original research
Growth estimates for solutions of nonhomogeneous linear complex differential equations
Janne Heittokangas, Risto Korhonen ja Jouni Rättyä. 2009. Annales academiae scientiarum fennicae-mathematica. 34: 145-156 A1 Journal article (refereed), original research
Value sharing results for shifts of meromorphic functions, and sufficient conditions for periodicity
J. Heittokangas, R. Korhonen, I. Laine, J. Rieppo, J. Zhang. 2009. Journal of mathematical analysis and applications. 355: 352-363 A1 Journal article (refereed), original research
Linear differential equations with coefficients in weighted Bergman and Hardy spaces
Janne Heittokangas, Risto Korhonen, Jouni Rättyä. 2008. Transactions of the american mathematical society. 360: 1035-1055 A1 Journal article (refereed), original research
Growth estimates for logarithmic derivatives of Blaschke products and of functions in the Nevanlinna class
Janne Heittokangas. 2007. Kodai Mathematical Journal. 30: 263-279 A1 Journal article (refereed), original research
Linear differential equations with solutions in Dirichlet type subspace of the Hardy space
J. Heittokangas, R. Korhonen, J. Rättyä. 2007. Nagoya Mathematical Journal. 187: 91-113 A1 Journal article (refereed), original research
Blaschke-oscillatory equations of the form f''+A(z)f=0
Janne Heittokangas. 2006. Journal of mathematical analysis and applications. 318: 120-133 A1 Journal article (refereed), original research
Fast growing solutions of linear differential equations in the unit disc
Janne Heittokangas, Risto Korhonen, Jouni Rättyä. 2006. Results in mathematics. 49: 265-278 A1 Journal article (refereed), original research
Solutions of f''+A(z)f=0 in the unit disc having Blaschke sequences as the zeros
Janne Heittokangas. 2005. Computational methods and function theory. 5: 49-63 A1 Journal article (refereed), original research
Solutions of f''+A(z)f=0 with prescribed sequences of zeros
J. Heittokangas, I. Laine. 2005. Acta Mathematica Universitatis Comenianae. 74: 287-307 A1 Journal article (refereed), original research
Generalized logarithmic derivative estimates of Gol'dberg-Grinshtein type
J. Heittokangas, R. Korhonen, J. Rättyä. 2004. Bulletin of the london mathematical society. 36: 105-114 A1 Journal article (refereed), original research
Growth estimates for solutions of linear complex differential equations
J. Heittokangas, R. Korhonen, J. Rättyä. 2004. Annales academiae scientiarum fennicae-mathematica. 29: 233-246 A1 Journal article (refereed), original research
Symposium on Complex Differential and Functional Equations
Rauno Aulaskari, Janne Heittokangas, Visa Latvala, Jari Taskinen (eds.). 2004. University of Joensuu, Department of Mathematics. Report Series. . Joensuun yliopisto C2 Edited book, conference proceedings or special issue of a journal
Linear differential equations and logarithmic derivative estimates
Igor Chyzhykov, Gary G. Gundersen, Janne Heittokangas. 2003. Proceedings of the london mathematical society. 86: 735-754 A1 Journal article (refereed), original research
Meromorphic solutions of generalized Schröder equations
Gary G. Gundersen, Janne Heittokangas, Ilpo Laine, Jarkko Rieppo, Dequi Yang. 2002. Aequationes mathematicae. 63: 110-135 A1 Journal article (refereed), original research
On meromorphic solutions of certain nonlinear differential equations
J. Heittokangas, R. Korhonen, I. Laine. 2002. Bulletin of the australian mathematical society. 66: 331-343 A1 Journal article (refereed), original research
Complex difference equations of Malmquist type
Janne Heittokangas, Risto Korhonen, Ilpo Laine, Jarkko Rieppo, Katsuya Tohge. 2001. Computational methods and function theory. 1: 27-39 A1 Journal article (refereed), original research
Differential equations with Hadamard products and Ruscheweyh derivatives
Janne Heittokangas. 2000. Mathematical Reports. 2(52): 467-484 A1 Journal article (refereed), original research
Meromorphic solutions of some linear functional equations
Janne Heittokangas, Ilpo Laine, Jarkko Rieppo, Degui Yang. 2000. Aequationes mathematicae. 60: 148-166 A1 Journal article (refereed), original research
On complex differential equations in the unit disc
Janne Heittokangas. 2000. Annales Academiae Scientiarum Fennicae. Mathematica. Dissertationes G4 Doctoral dissertation (monograph)

University of Eastern Finland Joensuu, Kuopio © University of Eastern Finland

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Janne Heittokangas

Research groups

Convergence of sub-series' and sub-signed series' in terms of the asymptotic ψ-density

Standard solutions of complex linear differential equations

A Continuous Transition from E-Sets to R-sets and Beyond

Asymptotic integration theory for f''+ P(z)f=0

Description of growth and oscillation of solutions of complex LDE’s

Irregular finite order solutions of complex LDE's in unit disc

Meromorphic Functions of Finite ϕ-order and Linear Askey—Wilson Divided Difference Equations

Opiskelun joustavuuden lisääminen matematiikan yliopisto-opintojen taitekohdassa

Oscillation of Solutions of LDE’s in Domains Conformally Equivalent to Unit Disc

Value distribution of exponential polynomials and their role in the theories of complex differential equations and oscillation theory

Contour integral solutions of linear differential equations which include a generalization of the Airy integral

Dual exponential polynomials and a problem of Ozawa

Meromorphic functions of finite φ-order and linear q-difference equations

On Petrenko's deviations and second order differential equations

On meromorphic solutions of non-linear differential equations of Tumura - Clunie type

On the limits of real-valued functions in sets involving Ψ-density, and applications

The asymptotic number of zeros of exponential sums in critical strips

Deficient Values of Solutions of Linear Differential Equations

Exponential polynomials in the oscillation theory

Generalization of Pólya's Zero Distribution Theory for Exponential Polynomials, and Sharp Results for Asymptotic Growth

On the number of linearly independent admissible solutions to linear differential and linear difference equations

Complex oscillation and nonoscillation results

Zero distribution and division results for exponential polynomials

Dual exponential polynomials and linear differential equations

On the relationship between the lower order of coefficients and the growth of solutions of differential equations

Completely regular growth solutions of second order complex linear differential equations

Second-order complex linear differential equations with special functions or extremal functions as coefficients

Functions of finite logarithmic order in the unit disc, Part I

Functions of finite logarithmic order in the unit disc, Part II

On alpha-Polynomial Regular Functions, with Applications to Ordinary Differential Equations

On the complexity of finding a necessary and sufficient condition for Blaschke-oscillatory equations

Zero separation results for solutions of second order linear differential equations

Blaschke Products and Their Applications

Exponential polynomials as solutions of certain nonlinear difference equations

New Findings on the Bank-Sauer Approach in Oscillation Theory

A unit disc analogue of the Bank-Laine conjecture does not hold

On interpolating Blaschke products and Blaschke-oscillatory equations

Possible Intervals for T- and M-Orders of Solutions of Linear Differential Equations in the Unit Disc

Uniqueness of meromorphic functions sharing values with their shifts

Zero distribution of solutions of complex linear differential equations determines growth of solutions

Sharp logarithmic derivative estimates with applications to ordinary differential equations in the unit disc

Finiteness of &phi: order of solutions of linear differential equations in the unit disc

Growth estimates for solutions of nonhomogeneous linear complex differential equations

Value sharing results for shifts of meromorphic functions, and sufficient conditions for periodicity

Linear differential equations with coefficients in weighted Bergman and Hardy spaces

Growth estimates for logarithmic derivatives of Blaschke products and of functions in the Nevanlinna class

Linear differential equations with solutions in Dirichlet type subspace of the Hardy space

Blaschke-oscillatory equations of the form f''+A(z)f=0

Fast growing solutions of linear differential equations in the unit disc

Solutions of f''+A(z)f=0 in the unit disc having Blaschke sequences as the zeros

Solutions of f''+A(z)f=0 with prescribed sequences of zeros

Generalized logarithmic derivative estimates of Gol'dberg-Grinshtein type

Growth estimates for solutions of linear complex differential equations

Symposium on Complex Differential and Functional Equations

Linear differential equations and logarithmic derivative estimates

Meromorphic solutions of generalized Schröder equations

On meromorphic solutions of certain nonlinear differential equations

Complex difference equations of Malmquist type

Differential equations with Hadamard products and Ruscheweyh derivatives

Meromorphic solutions of some linear functional equations

On complex differential equations in the unit disc