libbtf2 - 1:7.8.3+dfsg-2 main

Suitesparse is a collection of libraries for computations involving
sparse matrices.
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The BTF library is a software package for permuting a matrix into Block upper
Triangular Form. It includes a maximum transversal algorithm, which finds a
permutation of a square or rectangular matrix so that it has a zero-free
diagonal (if one exists); otherwise, it finds a maximal matching which
maximizes the number of nonzeros on the diagonal. The package also includes a
method for finding the strongly connected components of a graph. These two
methods together give the permutation to block upper triangular form.