1SuperLU is a general purpose library for the direct solution of large, 2sparse, nonsymmetric systems of linear equations on high performance 3machines. The library is written in C and is callable from either C or 4Fortran. The library routines will perform an LU decomposition with 5partial pivoting and triangular system solves through forward and back 6substitution. The LU factorization routines can handle non-square 7matrices but the triangular solves are performed only for square 8matrices. The matrix columns may be preordered (before factorization) 9either through library or user supplied routines. This preordering for 10sparsity is completely separate from the factorization. Working 11precision iterative refinement subroutines are provided for improved 12backward stability. Routines are also provided to equilibrate the 13system, estimate the condition number, calculate the relative backward 14error, and estimate error bounds for the refined solutions. 15