Chooses machine-dependent parameters for the local environment. More...
#include "slu_sdefs.h"
Include dependency graph for sp_ienv.c:
Functions | |
| int | sp_ienv (int ispec) |
| sp_ienv() is inquired to choose machine-dependent parameters for the local environment. More... | |
Function Documentation
◆ sp_ienv()
| int sp_ienv | ( | int | ispec | ) |
See ISPEC for a description of the parameters. This version provides a set of parameters which should give good, but not optimal, performance on many of the currently available computers. Users are encouraged to modify this subroutine to set the tuning parameters for their particular machine using the option and problem size information in the arguments.
- Parameters
-
[in] ispec Specifies the parameter to be returned as the value of SP_IENV.
= 1: the panel size w; a panel consists of w consecutive columns of matrix A in the process of Gaussian elimination. The best value depends on machine's cache characters.
= 2: the relaxation parameter relax; if the number of nodes (columns) in a subtree of the elimination tree is less than relax, this subtree is considered as one supernode, regardless of their row structures.
= 3: the maximum size for a supernode in complete LU.
= 4: the minimum row dimension for 2-D blocking to be used.
= 5: the minimum column dimension for 2-D blocking to be used.
= 6: the estimated fills factor for L and U, compared with A.
= 7: the maximum size for a supernode in ILU.
- Returns
- >= 0: the value of the parameter specified by ispec.
< 0: if SP_IENV = -k, the k-th argument had an illegal value.
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