Fredrik Johansson's website
I'm interested in arbitrary-precision arithmetic, polynomial arithmetic, and computation of special functions. I'm the main author of mpmath and Arb, and coauthor of FLINT. I'm currently a postdoc at RISC in Linz/Hagenberg, Austria, where I'm part of Manuel Kauers's START project and Peter Paule's Algorithmic Combinatorics group. See my blog and my Google+ page for updates, my GitHub account for code, and my RISC page for snail mail address, etc. Short vita:
- PhD in symbolic computation, RISC, Johannes Kepler University, Linz, March 2014.
- MSc in engineering physics, Chalmers University of Technology, Gothenburg, June 2010.
- Swedish citizen.
A fast algorithm for reversion of power series
Mathematics of Computation, vol ?, 2014?, pp. ?, DOI: 10.1090/S0025-5718-2014-02857-3
A bound for the error term in the Brent-McMillan algorithm (with Richard P. Brent)
to appear in Mathematics of Computation
Fast and rigorous computation of special functions to high precision
PhD thesis, RISC, Johannes Kepler University, Linz, 2014
Evaluating parametric holonomic sequences using rectangular splitting
ISSAC 2014 pp. 256-263, DOI: 10.1145/2608628.2608629
Using functional equations to enumerate 1324-avoiding permutations (with Brian Nakamura)
Advances in Applied Mathematics, vol 56, 2014, pp. 20-34, DOI: 10.1016/j.aam.2014.01.006
Rigorous high-precision computation of the Hurwitz zeta function and its derivatives
to appear in Numerical Algorithms
Ore polynomials in Sage (with Manuel Kauers and Maximilian Jaroschek)
to appear in Computer Algebra and Polynomials, Springer Lecture Notes in Computer Science
Arb: a C library for ball arithmetic
ACM Communications in Computer Algebra, vol 47, issue 4, December 2013, pp. 166-169, DOI: 10.1145/2576802.2576828
Finding hyperexponential solutions of linear ODEs by numerical evaluation (with Manuel Kauers and Marc Mezzarobba)
ISSAC 2013, pp. 211-218, DOI: 10.1145/2465506.2465513
Efficient implementation of the Hardy-Ramanujan-Rademacher formula
LMS Journal of Computation and Mathematics, vol 15, 2012, pp. 341-359, DOI: 10.1112/S1461157012001088
My most well-known project is probably mpmath, a Python library for arbitrary-precision floating-point arithmetic with support for complex numbers, special functions, numerical integration, linear algebra, etc. Notably, the selection of special functions may be the most extensive in any currently available open source project, comparable to Mathematica and Maple (see DLMF). The mpmath library has been cited in numerous publications. I started mpmath in 2007 and have written the majority of the code (various other people have made significant contributions).
I'm the author of Arb, a C library for asymptotically fast numerical computation with rigorous error bounds, using the concept of ball arithmetic. Arb supports complex numbers, polynomials, power series, matrices, and some special functions. I started developing Arb in 2012.
I'm a coauthor (since 2010) of FLINT, a C library for computational number theory with emphasis on asymptotically fast polynomial arithmetic. My work includes power series functions, exact linear algebra, number-theoretic special functions, and general optimizations.
In 2013, I helped develop ore_algebra, a Sage package for holonomic functions, together with Manuel Kauers and Maximilian Jaroschek. I've contributed to the Sage project since 2009, mainly by writing wrapper code for mpmath and FLINT. I attended Sage Days 15, 23, 24, 35. I also contributed extensively to the pure-Python computer algebra system SymPy from around 2007 to 2008, and designed SymPy's logo, but I'm no longer actively involved in that project.
- May 2014: Making change for 1020, seminar, TU Kaiserslautern
- March 2014: Making change for 1020, Algorithmic Combinatorics Seminar, RISC, Hagenberg
- October 2013: Progress on algorithms for high-precision evaluation of special functions, Algorithmic Combinatorics Seminar, RISC, Hagenberg
- July 2013: Efficient implementation of the Hardy-Ramanujan-Rademacher formula, 2013 SIAM Annual Meeting, San Diego, CA
- June 2013: Arb: a C library for ball arithmetic, ISSAC 2013, Boston, MA [Received the ISSAC 2013 Distinguished Software Presentation Award]
- June 2013: Finding Hyperexponential Solutions of Linear ODEs by Numerical Evaluation, ISSAC 2013, Boston, MA
- March 2013: Fast, rigorous, arbitrary precision numerics with ball arithmetic, Algorithmic Combinatorics Seminar, RISC, Hagenberg
- November 2012: Algorithms for hyperexponential solutions of differential equations, Algorithmic Combinatorics Seminar, RISC, Hagenberg
- May 2012: Fast special function computations with FLINT, RISC-DESY Workshop, RISC, Hagenberg.
- December 2011: Fast combinatorial special functions, Sage Days 35: Algorithms in Number Theory and FLINT, University of Warwick
- November 2011: Partitions in the quintillions or Billions of congruences, Algorithmic Combinatorics Seminar, RISC, Hagenberg
- November 2011: Fast reversion of power series, Algorithmic Combinatorics Seminar, RISC, Hagenberg
- July 2010: Computation of special functions in mpmath, Sage Days 24: Symbolic Computation in Differential Algebra and Special Functions, RISC, Hagenberg
- July 2010: Computation of special functions in mpmath, Sage Days 23: Number Theory and Algebra, Lorentz Center, Leiden
- May 2009: mpmath: arbitrary-precision floating-point arithmetic and special functions, Sage Days 15, University of Washington, Seattle, WA
On the off chance that you want to know what I'm listening to at the moment, check my last.fm account.
My Doom maps and related information.