spparms
Set parameters for sparse matrix routines
Syntax
spparms('key',value)
spparms
values = spparms
[keys,values] = spparms
spparms(values)
value = spparms('key')
spparms('default')
spparms('tight')
Description
spparms('key',value)
sets one or more of thetunableparameters used in the sparse routines. In ordinary use, you should never need to deal with this function.
The meanings of thekey
parameters are
'spumoni' |
Sparse Monitor flag: |
0 |
Produces no diagnostic output, the default |
1 |
Produces information about choice of algorithm based on matrix structure, and about storage allocation |
2 |
Also produces very detailed information about the sparse matrix algorithms |
'thr_rel', |
Minimum degree threshold is |
'exact_d' |
Nonzero to use exact degrees in minimum degree. Zero to use approximate degrees. |
'supernd' |
If positive, minimum degree amalgamates the supernodes every |
'rreduce' |
If positive, minimum degree does row reduction every |
'wh_frac' |
Rows with |
'autommd' |
Nonzero to use minimum degree (MMD) orderings with QR-based \ and |
'autoamd' |
Nonzero to use |
'piv_tol' |
Pivot tolerance used by the LU-based \ and /. |
'bandden' |
Band density used by \ and / for banded matrices. Band density is defined as (# nonzeros in the band)/(# nonzeros in a full band). If |
'umfpack' |
Nonzero to use UMFPACK instead of the v4 LU-based solver in |
'sym_tol' |
Symmetric pivot tolerance. See |
spparms
, by itself, prints a description of the current settings.
values = spparms
returns a vector whose components give the current settings.
[keys,values] = spparms
returns that vector, and also returns a character matrix whose rows are the keywords for the parameters.
spparms(values)
, with no output argument, sets all the parameters to the values specified by the argument vector.
value = spparms('key')
returns the current setting of one parameter.
spparms('default')
sets all the parameters to their default settings.
spparms('tight')
sets the minimum degree ordering parameters to theirtightsettings, which can lead to orderings with less fill-in, but which make the ordering functions themselves use more execution time.
The key parameters fordefault
andtight
settings are
Keyword |
Default |
Tight |
|
---|---|---|---|
values(1) |
'spumoni' |
|
|
values(2) |
'thr_rel' |
|
|
values(3) |
'thr_abs' |
|
|
values(4) |
'exact_d' |
|
|
values(5) |
'supernd' |
|
|
values(6) |
'rreduce' |
|
|
values(7) |
'wh_frac' |
|
|
values(8) |
'autommd' |
|
|
values(9) |
'autoamd' |
|
|
values(10) |
'piv_tol' |
|
|
values(11) |
'bandden' |
|
|
values(12) |
'umfpack' |
|
|
values(13) |
'sym_tol' |
|