IMI Interdisciplinary Mathematics InstituteCollege of Arts and Sciences

Pencho Petrushev

  • Professor
  • Department of Mathematics
  • University of South Carolina

  • Director
  • Interdisciplinary Mathematics Institute
  • University of South Carolina


Doc. of Sci. Mathematics Sofia University, Bulgaria 1983
Ph.D. Mathematics Sofia University, Bulgaria 1977
B.S. Mathematics Sofia University, Bulgaria 1972


2009 – Present Director Interdisciplinary Mathematics Institute, Univ. of South Carolina
1996 – Present Professor Department of Mathematics, Univ. of South Carolina
1986 – 1996 Professor Inst. of Mathematics, Bulgarian Acad. of Sciences
1982 – 1986 Senior Research Fellow Inst. of Mathematics, Bulgarian Acad. of Sciences
1977 – 1982 Research Fellow Inst. of Mathematics, Bulgarian Acad. of Sciences


Research Interests

General: Approximation Theory, Harmonic Analysis, Numerical Analysis

  • Spaces of distributions such as Hardy, Besov and Triebel-Lizorkin spaces in harmonic, nonclassical, anisotropic and geometric settings;
  • Construction of bases and frames (needlets) for Besov and Triebel-Lizorkin spaces in nonclassical and geometric settings;
  • Nonlinear approximation from rational functions, splines, frames, ridge functions and more general dictionaries;
  • Application of spherical needlets to approximation and fast evaluation of quantities represented in high degree surface or solid spherical harmonics; and
  • Reproduction of sound from optical sound tracks of digital scans of motion picture films.

Current Projects

  • Approximation and evaluation of quantities represented in spherical harmonics - This is a joint project with Kamen Ivanov (Bulgarian Academy of Sciences) for application of highly localized reproducing kernels (spherical needlets) to approximation and evaluation of quantities represented in surface or solid spherical harmonics. The main targeted application of this development is to Geopotential and Geomagnetic field modeling. This research is supported by NGA/DOD: grant HM01771210004 "Highly Effective Compression and Evaluation of Geodetic Quantities" (August 15, 2012 - August 14, 2017). The purpose of this project is to develop algorithms and software for fast, accurate, stable, and memory efficient evaluation of geodetic quantities represented in high degree (> 2,000) surface or solid spherical harmonics at many (millions) scattered points on the surface of the Earth or in the space above its surface.
  • Reproduction of sound from optical sound tracks of motion picture films - This is a collaborative research project with Greg Wilsbacher from the USC Moving Image Research Collections (MIRC). The goal of the project is to develop an open-source software application to directly reproduce the optical sound tracks of motion picture films from digital scans. This is part of the process of migrating the twentieth century film production into the digital realm with the ultimate goal of preserving the twentieth-century's cultural and historical record for future generations. Our prior joint grant: "An Open Source Application for Image-Based Digital Reproduction of Optical Film Sound" (May 2011 - May 2014) from the National Endowment for the Humanities (NEH), produced an open-source software application for reproduction of sound. For details, visit AEO-Light 2.0. Our current project (Phase II development) "AEO-Light 2.0: An Open Source Application for Image-Based Digital Reproduction of Optical Film Sound," is a two-year grant from NEH (January 2015 - December 2016). Scott Johnson (IMI) and David Hughey (grad student in the Department of Mathematics) are also involved in this project.


Teaching Activities

Current Courses

  • Math 750 - Fourier Analysis

Previous Courses

  • Undergraduate courses: Calculus I (Math 141), Calculus II (Math 142), Vector Calculus (Math 241), Elementary Differential Equations (Math 242), Ordinary Differential Equations (Math 520), Linear Algebra (Math 544), Analysis I (Math 554), Analysis II (Math 555).
  • Graduate courses: Analysis I (Math 703), Analysis II (Math 704), Applied Mathematics I (Math 720), Applied Mathematics II (Math 721), Approximation Theory (Math 725), Nonlinear Approximation (Math 729), Fourier Analysis (Math 750), Maximal Operators, Littlewood-Paley Theory, and Bases (Math 758P).


Honors and Other Special Scientific Recognition

  • The 2010 USC Educational Foundation Award for Research in Science, Mathematics, and Engineering
  • The 2010 Manuel Garcia Prize from the International Association of Logopedics and Phoniatrics for outstanding contributions to the official journal of IALP and to the field of communication sciences and disorders, jointly with D. Deliyski, H. Bonilha, T. Gerlach, B. Martin-Harris, and R. Hillman
  • The 1989 Bulgarian Mathematical Scienece Award "N. Obreshkov'' awarded by the Bulgarian Academy of Sciences and Sofia University


5 Selected Publications

  • G. Kerkyacharian, P. Petrushev, Heat kernel based decomposition of spaces of distributions in the framework of Dirichlet spaces, Trans. Amer. Math. Soc. 367 (2015), 121–189.
  • G. Kyriazis, P. Petrushev, Rational bases for spaces of holomorphic functions in the disc, J. Lond. Math. Soc. (2) 89 (2014), 434–460.
  • F. Narcowich, P. Petrushev, and J. Ward, Decomposition of Besov and Triebel-Lizorkin spaces on the sphere, J. Funct. Anal. 238 (2006), 530–564.
  • G. Kyriazis, P. Petrushev, New bases for Triebel-Lizorkin and Besov spaces, Trans. Amer. Math. Soc. 354 (2002), 749–776.
  • A. Cohen, R. DeVore, P. Petrushev, and H. Xu, Nonlinear approximation and the space $BV(R^2)$, Amer. J. Math. 121 (1999), 587–628.


IMI Preprints and Seminars

Go to the list of 49 preprints and 4 seminars by Pencho Petrushev.


Curriculum Vitae

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