Qoca is a GPL library for incrementally solving systems of linear equations with various goal functions. It contains a robust implementation of Cassowary, a popular linear programming algorithm for handling Manhattan goal functions. It is used in several free software projects and is maintained at Monash University. It is available in a C++ or a Java version, and provides language bindings for Python and Perl.

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The CVS host listed on the download page no longer exists. The sources no longer compile out of the box (2013). Perhaps this 2003 software is unmaintained today.