This is the 2-D convection-diffusion operator
-e*laplacian(u) + u_y
on the unit square with Dirichlet boundary conditions. The discretisation is done using finite differences (see, e.g., [1]), resulting in large, sparse matrices. The code is based on a routine by Daniel Loghin.
[1]: L. Hemmingsson, "A Semi-circulant Preconditioner for the Convection-Diffusion Equation", Numer. Math 81, 1998, 211-248
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