Symplectic groupoid of unipotent nxn upper-triangular matrices is formed by pairs (B, A) where B is a nondegenerate nxn matrix, A is a unipotent upper-triangular nxn matrix, and BAB^t is unipotent ...

Arranging the sparse circuit matrix into a diagonal block upper triangular form is the first step of the KLU algorithm. This paper presents the two steps of the parallel algorithm, running in a ...