mitchell_10, a FreeFem++ code which sets up and solves Mitchell's problem 10, "the interior line singularity".
The computer code and data files described and made available on this web page are distributed under the MIT license
A web site at NIST describes these and many other problems: http://math.nist.gov/amr-benchmark/index.html
mitchell_10a defines the "interior line singularity" problem on the [-1,+1]x[-1,+1] square with parameters ALPHA = 2.5, BETA = 0.0.
mitchell_10b defines the "interior line singularity" problem on the [-1,+1]x[-1,+1] square with parameters ALPHA = 1.1, BETA = 0.0.
mitchell_10c defines the "interior line singularity" problem on the [-1,+1]x[-1,+1] square with parameters ALPHA = 1.5, BETA = 0.6.