/* -------------------------------------------------------------------------- */
  /* UMFPACK Copyright (c) Timothy A. Davis, CISE,                              */
  /* Univ. of Florida.  All Rights Reserved.  See ../Doc/License for License.   */
  /* web: http://www.cise.ufl.edu/research/sparse/umfpack                       */
  /* -------------------------------------------------------------------------- */
  
  GLOBAL void UMF_2by2
  (
      Int n,
      const Int Ap [ ],
      const Int Ai [ ],
      const double Ax [ ],
  #ifdef COMPLEX
      const double Az [ ],
  #endif
      double tol,
      Int scale,
      Int Cperm1 [ ],
  #ifndef NDEBUG
      Int Rperm1 [ ],
  #endif
      Int InvRperm [ ],
      Int n1,
      Int nempty,
      Int Degree [ ],
      Int P [ ],
      Int *p_nweak,
      Int *p_nmatched,
      Int Ri [ ],
      Int Rp [ ],
      double Rs [ ],
      Int Head [ ],
      Int Next [ ],
      Int Si [ ],
      Int Sp [ ]
  ) ;