Hans Petter Langtangen (1962 - 2016) was a professor of computer science at the University of Oslo. He was formerly a professor of mechanics and was the Director of "Center for Biomedical Computing", a Norwegian Center of Excellence at the Simula Research Laboratory in Oslo. Langtangen has more than 100 scientific publications, including journal papers and many books, e.g., the bestseller TCSE 6 "A Primer on Scientific Programming with Python" (editions 1 - 5). He has also developed open source and commercial software systems for computational sciences.” Kent-Andre Mardal is a professor of mechanics at the University of Oslo and an adjunct research scientist at Simula Research Laboratory. He has published more than 80 scientific publications, including journal papers, one co-authored book and the co-edited the book about the FEniCS project, for which he was a core developer for many years.

• Preface.- Quick overview of the finite element method.- Function approximation by global functions.- Function approximation by finite elements.- Variational formulations with global elements.- Variational formulations with finite elements.- Time-dependent variational forms.- Variational forms for systems of PDEs.- Nonlinear Problems.- Variational forms for linear systems.- Useful formulas.

“Hans Petter Langtangen's spirit and passion for computational science, education, and interdisciplinary collaboration continues to manifest through a text that is lively, conversational, informative, approachable, and interactive.” (Akil Narayan, SIAM Review, Vol. 62 (4), 2020)“Introduction to Numerical Methods for Variational Problems is well-suited for undergraduate or beginning graduate students in applied mathematics, physics, or engineering that want to begin to learn about the numerical analysis of or scientific computing with PDEs. … Introduction to Numerical Methods for Variational Problems seems to me like a very good place to start.” (MAA Reviews, March 5, 2020)