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/*****************************************************************************
/
/ SPACE (SPArse Cholesky Elimination) Library: ms.c
/
/ author J"urgen Schulze, University of Paderborn
/ created 01jan04
/
/ This file contains functions dealing with the multisector object
/
******************************************************************************
Data type: struct multisector
graph_t *G; pointer to original graph
int *stage; stage[u]=i => node u will be elim. in stage i
int nstages; number of stages
int nnodes; number of nodes in multisector
int totmswght; weigth of nodes in multisector
Comments:
o Structure does not own graph object G => it will not be freed
Note: G is the original graph
Methods in lib/multisector.c:
- ms = newMultisector(graph_t *G);
o Initial: nstages = nnodes = totmswght = 0;
- void freeMultisector(ms_t *ms);
- ms = trivialMultisector(graph_t *G);
o allocates memory for the multisector object by a call to newMultisector
and sets stage[u] = 0 for all vertices u and nstages = 1; the trivial
multisector can be used for pure bottom-up orderings
- ms = constructMultisector(graph_t *G, options_t* options, timings_t *cpus);
o MASTER_FUNCTION: computes a multisector for G according to the specified
ordtype e { MINIMUM_PRIORITY, INCOMPLETE_ND, MULTISECTION,
TRISTAGE_MULTISECTION }
MINIMUM_PRIORTY:
return the multisector obtained by a call to trivialMultisector
INCOMPLETE_ND, MULTISECTION, TRISTAGE_MULTISECTION:
build separator tree by calling buildNDtree and extract multisector
by calling extractMS2stage (MULTISECTION) or extractMSmultistage
(INCOMPLETE_ND, TRISTAGE_MULTISECTION)
o used options: (also see buildNDtree)
OPTION_ORDTYPE, OPTION_DOMAIN_SIZE, OPTION_MSGLVL, OPTION_NODE_SELECTION3
o returned timings: (see buildNDtree)
TIME_INITDOMDEC, TIME_COARSEDOMDEC, TIME_INITSEP, TIME_REFINESEP
TIME_MULTILEVEL, TIME_SMOOTH
- ms = extractMS2stage(nestdiss_t *ndroot);
o extracts a 2-stage multisector from the nested dissection tree with root
ndroot: stage[u] = 0 => u belongs to a domain
stage[u] = 1 => u belongs to the multisector
and nstages = 2; the 2-stage multisector can be used for classical
multisection orderings
- ms = extractMSmultistage(nestdiss_t *ndroot);
o extracts a multi-stage multisector from the nested dissection tree at
ndroot: stage[u] = 0 => u belongs to a domain
stage[u] = i, i > 0 => u belongs to the multisector, i.e.:
stage[u] = 1 => u belongs to a leaf separator
:
stage[u] = nstages-1 => u belongs to the root separator
the multisector can be used for incomplete nested dissection orderings
or for three-stage multisection orderings
******************************************************************************/
#include <space.h>
/*****************************************************************************
******************************************************************************/
multisector_t*
newMultisector(graph_t *G)
{ multisector_t *ms;
mymalloc(ms, 1, multisector_t);
mymalloc(ms->stage, G->nvtx, PORD_INT);
ms->G = G;
ms->nstages = 0;
ms->nnodes = 0;
ms->totmswght = 0;
return(ms);
}
/*****************************************************************************
******************************************************************************/
void
freeMultisector(multisector_t *ms)
{
free(ms->stage);
free(ms);
}
/*****************************************************************************
******************************************************************************/
multisector_t*
trivialMultisector(graph_t *G)
{ multisector_t *ms;
PORD_INT *stage, nvtx, u;
/* -----------------------------------------------------------------
allocate memory for the multisector object and init. stage vector
----------------------------------------------------------------- */
nvtx = G->nvtx;
ms = newMultisector(G);
stage = ms->stage;
for (u = 0; u < nvtx; u++)
stage[u] = 0; /* no vertex belongs to a separator */
/* -------------------------------
finalize the multisector object
------------------------------- */
ms->nstages = 1;
ms->nnodes = 0;
ms->totmswght = 0;
return(ms);
}
/*****************************************************************************
******************************************************************************/
multisector_t*
constructMultisector(graph_t *G, options_t* options, timings_t *cpus)
{ multisector_t *ms;
nestdiss_t *ndroot;
PORD_INT *map, nvtx, ordtype;
nvtx = G->nvtx;
/* ------------------------------
check number of nodes in graph
------------------------------ */
/* -----------------------------------
JY: inserted the condition
"&& (options[OPTION_MSGLVL] > 0)"
below, to avoid systematic printing
----------------------------------- */
if ((nvtx <= MIN_NODES) && (options[OPTION_ORDTYPE] != MINIMUM_PRIORITY)
&& (options[OPTION_MSGLVL] > 0))
{ printf("\nWarning in constructMultisector\n"
" graph has less than %d nodes, skipping separator construction\n\n",
MIN_NODES);
options[OPTION_ORDTYPE] = MINIMUM_PRIORITY;
}
/* --------------------------------------------------------
determine the multisector according to the ordering type
-------------------------------------------------------- */
ordtype = options[OPTION_ORDTYPE];
switch(ordtype)
{ case MINIMUM_PRIORITY:
ms = trivialMultisector(G);
break;
case INCOMPLETE_ND:
case MULTISECTION:
case TRISTAGE_MULTISECTION:
mymalloc(map, nvtx, PORD_INT);
ndroot = setupNDroot(G, map);
buildNDtree(ndroot, options, cpus);
if (ordtype == MULTISECTION)
ms = extractMS2stage(ndroot);
else
ms = extractMSmultistage(ndroot);
freeNDtree(ndroot);
freeNDnode(ndroot);
free(map);
break;
default:
fprintf(stderr, "\nError in function constructMultisector\n"
" unrecognized ordering type %d\n", ordtype);
quit();
}
return(ms);
}
/*****************************************************************************
******************************************************************************/
multisector_t*
extractMS2stage(nestdiss_t *ndroot)
{ multisector_t *ms;
nestdiss_t *nd, *parent;
PORD_INT *stage, *intvertex, *intcolor;
PORD_INT nvint, nnodes, totmswght, i;
/* -----------------------------------------------------------------
allocate memory for the multisector object and init. stage vector
----------------------------------------------------------------- */
ms = trivialMultisector(ndroot->G);
stage = ms->stage;
/* ------------------------------------------------------------
extract the stages of the separator vertices:
stage[u] = 1, iff u belongs to a separator
------------------------------------------------------------ */
nnodes = totmswght = 0;
for (nd = ndroot; nd->childB != NULL; nd = nd->childB);
while (nd != ndroot)
{ parent = nd->parent;
if ((parent == NULL) || (parent->childB == NULL)
|| (parent->childW == NULL))
{ fprintf(stderr, "\nError in function extractMS2stage\n"
" nested dissection tree corrupted\n");
quit();
}
if (parent->childB == nd) /* left subtree of parent visited */
for (nd = parent->childW; nd->childB != NULL; nd = nd->childB);
else /* right subtree of parent visited */
{ nd = parent; /* extract the separator of parent */
totmswght += nd->cwght[GRAY];
nvint = nd->nvint;
intvertex = nd->intvertex;
intcolor = nd->intcolor;
for (i = 0; i < nvint; i++)
if (intcolor[i] == GRAY)
{ nnodes++;
stage[intvertex[i]] = 1;
}
}
}
/* ------------------------------------------
finalize the multisector object and return
------------------------------------------ */
ms->nstages = 2;
ms->nnodes = nnodes;
ms->totmswght = totmswght;
return(ms);
}
/*****************************************************************************
******************************************************************************/
multisector_t*
extractMSmultistage(nestdiss_t *ndroot)
{ multisector_t *ms;
nestdiss_t *nd, *parent;
PORD_INT *stage, *intvertex, *intcolor;
PORD_INT nvtx, nvint, maxstage, istage, nnodes, totmswght, i, u;
/* -----------------------------------------------------------------
allocate memory for the multisector object and init. stage vector
----------------------------------------------------------------- */
ms = trivialMultisector(ndroot->G);
stage = ms->stage;
/* ------------------------------------------------------------
extract the stages of the separator vertices:
stage[u] = i, i>0, iff u belongs to a separator in depth i-1
------------------------------------------------------------ */
maxstage = nnodes = totmswght = 0;
for (nd = ndroot; nd->childB != NULL; nd = nd->childB);
while (nd != ndroot)
{ parent = nd->parent;
if ((parent == NULL) || (parent->childB == NULL)
|| (parent->childW == NULL))
{ fprintf(stderr, "\nError in function extractMSmultistage\n"
" nested dissection tree corrupted\n");
quit();
}
if (parent->childB == nd) /* left subtree of parent visited */
for (nd = parent->childW; nd->childB != NULL; nd = nd->childB);
else /* right subtree of parent visited */
{ nd = parent; /* extract the separator of parent */
istage = nd->depth + 1; /* sep. vertices belong to this stage */
maxstage = max(maxstage, istage);
totmswght += nd->cwght[GRAY];
nvint = nd->nvint;
intvertex = nd->intvertex;
intcolor = nd->intcolor;
for (i = 0; i < nvint; i++)
if (intcolor[i] == GRAY)
{ nnodes++;
stage[intvertex[i]] = istage;
}
}
}
/* --------------------------------------------------------------------
we have: stage[u] = 0 => u belongs to a domain
stage[u] = 1 => u belongs to the root separator (depth = 0)
:
stage[u] = maxstage => u belongs to a leaf separator
but we must eliminate the separators in a bottom-up fashion; we like
to have: stage[u] = 0 => u belongs to a domain
stage[u] = 1 => u belongs to a leaf separator
:
stage[u] = maxstage => u belongs to the root separator
-------------------------------------------------------------------- */
nvtx = ndroot->G->nvtx;
for (u = 0; u < nvtx; u++)
if (stage[u] > 0)
stage[u] = maxstage - stage[u] + 1;
/* ------------------------------------------
finalize the multisector object and return
------------------------------------------ */
ms->nstages = maxstage + 1;
ms->nnodes = nnodes;
ms->totmswght = totmswght;
return(ms);
}
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