forked from bartvdbraak/blender
75 lines
2.2 KiB
C
75 lines
2.2 KiB
C
/** \file opennl/superlu/relax_snode.c
|
|
* \ingroup opennl
|
|
*/
|
|
/*
|
|
* -- SuperLU routine (version 2.0) --
|
|
* Univ. of California Berkeley, Xerox Palo Alto Research Center,
|
|
* and Lawrence Berkeley National Lab.
|
|
* November 15, 1997
|
|
*
|
|
*/
|
|
/*
|
|
Copyright (c) 1994 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.
|
|
*/
|
|
|
|
#include "ssp_defs.h"
|
|
|
|
void
|
|
relax_snode (
|
|
const int n,
|
|
int *et, /* column elimination tree */
|
|
const int relax_columns, /* max no of columns allowed in a
|
|
relaxed snode */
|
|
int *descendants, /* no of descendants of each node
|
|
in the etree */
|
|
int *relax_end /* last column in a supernode */
|
|
)
|
|
{
|
|
/*
|
|
* Purpose
|
|
* =======
|
|
* relax_snode() - Identify the initial relaxed supernodes, assuming that
|
|
* the matrix has been reordered according to the postorder of the etree.
|
|
*
|
|
*/
|
|
register int j, parent;
|
|
register int snode_start; /* beginning of a snode */
|
|
|
|
ifill (relax_end, n, EMPTY);
|
|
for (j = 0; j < n; j++) descendants[j] = 0;
|
|
|
|
/* Compute the number of descendants of each node in the etree */
|
|
for (j = 0; j < n; j++) {
|
|
parent = et[j];
|
|
if ( parent != n ) /* not the dummy root */
|
|
descendants[parent] += descendants[j] + 1;
|
|
}
|
|
|
|
/* Identify the relaxed supernodes by postorder traversal of the etree. */
|
|
for (j = 0; j < n; ) {
|
|
parent = et[j];
|
|
snode_start = j;
|
|
while ( parent != n && descendants[parent] < relax_columns ) {
|
|
j = parent;
|
|
parent = et[j];
|
|
}
|
|
/* Found a supernode with j being the last column. */
|
|
relax_end[snode_start] = j; /* Last column is recorded */
|
|
j++;
|
|
/* Search for a new leaf */
|
|
while ( descendants[j] != 0 && j < n ) j++;
|
|
}
|
|
|
|
/*printf("No of relaxed snodes: %d; relaxed columns: %d\n",
|
|
nsuper, no_relaxed_col); */
|
|
}
|