Postdoctoral Fellow
Email:  schnake(at)ou(dot)edu 
Office:  PHSC 1024 
Research Areas:
Research Interests:
Applications
Recent Publications
[4]  Xiaobing Feng, Thomas Lewis, and Stefan Schnake. Analysis of the Vanishing Moment Method and its Finite Element Approximations for Secondorder Linear Elliptic PDEs in Nondivergence Form. Methods and Applications of Analysis, 2017 (submitted). [ arXiv ] 
[3]  Xiaobing Feng and Stefan Schnake. A Discontinuous Ritz Method for a Class of Calculus of Variations Problems. International Journal of Numerical Analysis and Modeling, 16(3):340356, 2019. [ http  arXiv ] 
[2]  Xiaobing Feng and Stefan Schnake. An enhanced finite element method for a class of variational problems exhibiting the Lavrentiev gap phenomenon. Communications in Computational Physics, 24(2):576592, 2018. [ http  arXiv ] 
[1] 
Xiaobing Feng, Michael Neilan, and Stefan Schnake.
Interior penalty discontinuous galerkin methods for second order
linear nondivergence form elliptic pdes.
Journal of Scientific Computing, 74(3):16511676, Mar 2018.
[ bib 
DOI 
http 
arXiv ]

I have developed a MATLAB toolbox to implement the Discontinuous Galerkin Finite Element Differential Calculus found here. This software allows one to take a discrete derivative of functions that are classically, weakly, and distributionally differentiable in one or two dimensions.
The documentation is available here and the code is available here for you to test and use. Note: This code is used asis. I assume no loss or liability for the use of this code.