/[escript]/trunk/paso/src/SystemMatrixPattern_mis.c
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Contents of /trunk/paso/src/SystemMatrixPattern_mis.c

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Revision 1028 - (show annotations)
Wed Mar 14 00:15:24 2007 UTC (12 years, 5 months ago) by gross
File MIME type: text/plain
File size: 4917 byte(s)
modifications to be compliant with _WIN32. The substitutes for asinh, acosh, atanh are still missing (erf will through an exception)
1 /* $Id$ */
2
3 /*
4 ********************************************************************************
5 * Copyright 2006 by ACcESS MNRF *
6 * *
7 * http://www.access.edu.au *
8 * Primary Business: Queensland, Australia *
9 * Licensed under the Open Software License version 3.0 *
10 * http://www.opensource.org/licenses/osl-3.0.php *
11 ********************************************************************************
12 */
13
14 /**********************************************************************/
15
16 /* Paso: SystemMatrixPattern: Paso_SystemMatrixPattern_mis
17
18 searches for a maximal independent set MIS in the matrix pattern
19 vertices in the maximal independent set are marked in mis_marker
20 nodes to be considered are marked by -1 on the input in mis_marker
21
22 */
23 /**********************************************************************/
24
25 /* Copyrights by ACcESS Australia 2003,2004,2005 */
26 /* Author: gross@access.edu.au */
27
28 /**************************************************************/
29
30 #ifdef PASO_MPI
31 #include <mpi.h>
32 #endif
33 #include "Paso.h"
34 #include "PasoUtil.h"
35 #include "SystemMatrixPattern.h"
36
37
38 /* used to generate pseudo random numbers: */
39
40 static double Paso_SystemMatrixPattern_mis_seed=.4142135623730951;
41
42
43 /***************************************************************/
44
45 #define IS_AVAILABLE -1
46 #define IS_IN_MIS_NOW -2
47 #define IS_IN_MIS -3
48 #define IS_CONNECTED_TO_MIS -4
49
50 void Paso_SystemMatrixPattern_mis(Paso_SystemMatrixPattern* pattern_p, index_t* mis_marker) {
51
52 index_t index_offset=(pattern_p->type & PATTERN_FORMAT_OFFSET1 ? 1:0);
53 dim_t i;
54 double *value;
55 index_t naib,iptr;
56 bool_t flag;
57 dim_t n=pattern_p->n_ptr;
58 if (pattern_p->type & PATTERN_FORMAT_SYM) {
59 Paso_setError(TYPE_ERROR,"Paso_SystemMatrixPattern_mis: symmetric matrix pattern is not supported yet");
60 return;
61 }
62 value=TMPMEMALLOC(n,double);
63 if (!Paso_checkPtr(value)) {
64
65
66 /* is there any vertex available ?*/
67 while (Paso_Util_isAny(n,mis_marker,IS_AVAILABLE)) {
68 /* step 1: assign a random number in [0,1] to each vertex */
69 /* step 2: is the vertex is available, check if its value is the smaller than all values of its naigbours
70 if the answer is yes, the vertex is put into the independend set and all
71 its naighbours are removed from the graph by setting it mis_marker to FALSE */
72
73 /* step 2: is the vertex is available, check if its value is the smaller than all values of its naigbours */
74
75 /* assign random number in [0,1] to each vertex */
76 #pragma omp parallel for private(i) schedule(static)
77 for (i=0;i<n;++i) {
78 if (mis_marker[i]==IS_AVAILABLE) {
79 value[i]=fmod(Paso_SystemMatrixPattern_mis_seed*(i+1),1.);
80 } else {
81 value[i]=2.;
82 }
83 }
84 /* update the seed */
85 /* Paso_SystemMatrixPattern_mis_seed=fmod(sqrt(Paso_SystemMatrixPattern_mis_seed*(n+1)),1.); */
86 /* detect independent vertices as those vertices that have a value less than all values of its naigbours */
87 #pragma omp parallel for private(naib,i,iptr,flag) schedule(static)
88 for (i=0;i<n;++i) {
89 if (mis_marker[i]==IS_AVAILABLE) {
90 flag=IS_IN_MIS_NOW;
91 for (iptr=pattern_p->ptr[i]-index_offset;iptr<pattern_p->ptr[i+1]-index_offset; ++iptr) {
92 naib=pattern_p->index[iptr]-index_offset;
93 if (naib!=i && value[naib]<=value[i]) {
94 flag=IS_AVAILABLE;
95 break;
96 }
97 }
98 mis_marker[i]=flag;
99 }
100 }
101 /* detect independent vertices as those vertices that have a value less than all values of its naigbours */
102 #pragma omp parallel for private(naib,i,iptr) schedule(static)
103 for (i=0;i<n;i++) {
104 if (mis_marker[i]==IS_IN_MIS_NOW) {
105 for (iptr=pattern_p->ptr[i]-index_offset;iptr<pattern_p->ptr[i+1]-index_offset; ++iptr) {
106 naib=pattern_p->index[iptr]-index_offset;
107 if (naib!=i) mis_marker[naib]=IS_CONNECTED_TO_MIS;
108 }
109 mis_marker[i]=IS_IN_MIS;
110 }
111 }
112 }
113 /* swap to TRUE/FALSE in mis_marker */
114 #pragma omp parallel for private(i) schedule(static)
115 for (i=0;i<n;i++) mis_marker[i]=(mis_marker[i]==IS_IN_MIS);
116 }
117 TMPMEMFREE(value);
118 }
119 #undef IS_AVAILABLE
120 #undef IS_IN_MIS_NOW
121 #undef IS_IN_MIS
122 #undef IS_CONNECTED_TO_MIS

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