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/*
Copyright (c) 2003, The Regents of the University of California, through
Lawrence Berkeley National Laboratory (subject to receipt of any required
approvals from U.S. Dept. of Energy)
All rights reserved.
The source code is distributed under BSD license, see the file License.txt
*/
/*
Copyright (c) 1997 by Xerox Corporation. All rights reserved.
THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY
EXPRESSED OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
Permission is hereby granted to use or copy this program for any
purpose, provided the above notices are retained on all copies.
Permission to modify the code and to distribute modified code is
granted, provided the above notices are retained, and a notice that
the code was modified is included with the above copyright notice.
*/
/*
* File name: sp_ienv.c
* History: Modified from lapack routine ILAENV
*/
#include "slu_Cnames.h"
extern void xerbla_();
int
sp_ienv(int ispec)
{
/*
Purpose
=======
sp_ienv() is inquired to choose machine-dependent parameters for the
local environment. 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.
Arguments
=========
ISPEC (input) int
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;
= 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;
(SP_IENV) (output) int
>= 0: the value of the parameter specified by ISPEC
< 0: if SP_IENV = -k, the k-th argument had an illegal value.
=====================================================================
*/
int i;
switch (ispec) {
case 1: return (10);
case 2: return (5);
case 3: return (100);
case 4: return (200);
case 5: return (40);
case 6: return (20);
}
/* Invalid value for ISPEC */
i = 1;
xerbla_("sp_ienv", &i);
return 0;
} /* sp_ienv_ */
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