Function Reference
— Loadable Function: spparms ()
— Loadable Function: vals = spparms ()
— Loadable Function: [keys, vals] = spparms ()
— Loadable Function: val = spparms (key)
— Loadable Function: spparms (vals)
— Loadable Function: spparms ('defaults')
— Loadable Function: spparms ('tight')
— Loadable Function: spparms (key, val)

Sets or displays the parameters used by the sparse solvers and factorization functions. The first four calls above get information about the current settings, while the others change the current settings. The parameters are stored as pairs of keys and values, where the values are all floats and the keys are one of the strings

  • spumoni Printing level of debugging information of the solvers (default 0)
  • ths_rel Included for compatibility. Not used. (default 1)
  • ths_abs Included for compatibility. Not used. (default 1)
  • exact_d Included for compatibility. Not used. (default 0)
  • supernd Included for compatibility. Not used. (default 3)
  • rreduce Included for compatibility. Not used. (default 3)
  • wh_frac Included for compatibility. Not used. (default 0.5)
  • autommd Flag whether the LU/QR and the '\' and '/' operators will automatically use the sparsity preserving mmd functions (default 1)
  • autoamd Flag whether the LU and the '\' and '/' operators will automatically use the sparsity preserving amd functions (default 1)
  • piv_tol The pivot tolerance of the UMFPACK solvers (default 0.1)
  • sym_tol The pivot tolerance of the UMFPACK symmetric solvers (default 0.001)
  • bandden The density of non-zero elements in a banded matrix before it is treated by the LAPACK banded solvers (default 0.5)
  • umfpack Flag whether the UMFPACK or mmd solvers are used for the LU, '\' and '/' operations (default 1)

The value of individual keys can be set with spparms (key, val). The default values can be restored with the special keyword 'defaults'. The special keyword 'tight' can be used to set the mmd solvers to attempt for a sparser solution at the potential cost of longer running time.