Index column_dfs(const Index m, const Index jcol, IndexVector &perm_r, Index maxsuper, Index &nseg, BlockIndexVector lsub_col, IndexVector &segrep, BlockIndexVector repfnz, IndexVector &xprune, IndexVector &marker, IndexVector &parent, IndexVector &xplore, GlobalLU_t &glu)
Performs a symbolic factorization on column jcol and decide the supernode boundary.