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[project @ 2005-02-25 19:55:24 by jwe]
author jwe
date Fri, 25 Feb 2005 19:55:28 +0000
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children 49ff3dd744ee
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5163:9f3299378193 5164:57077d0ddc8e
1 /* ========================================================================== */
2 /* === colamd and symamd example ============================================ */
3 /* ========================================================================== */
4
5 /*
6 colamd example of use, to order the columns of a 5-by-4 matrix with
7 11 nonzero entries in the following nonzero pattern, with default knobs.
8
9 x 0 x 0
10 x 0 x x
11 0 x x 0
12 0 0 x x
13 x x 0 0
14
15 symamd example of use, to order the rows and columns of a 5-by-5
16 matrix with 13 nonzero entries in the following nonzero pattern,
17 with default knobs.
18
19 x x 0 0 0
20 x x x x 0
21 0 x x 0 0
22 0 x 0 x x
23 0 0 0 x x
24
25 (where x denotes a nonzero value).
26
27 September 8, 2003. Version 2.3.
28
29 See http://www.cise.ufl.edu/research/sparse/colamd/ (the colamd.c file)
30 for the routines this program calls, and for the License.
31 */
32
33 /* ========================================================================== */
34
35 #include <stdio.h>
36 #include "colamd.h"
37
38 #define A_NNZ 11
39 #define A_NROW 5
40 #define A_NCOL 4
41 #define ALEN (COLAMD_RECOMMENDED (A_NNZ, A_NCOL, A_NROW))
42
43 #define B_NNZ 4
44 #define B_N 5
45
46 int main (int argc, char **argv)
47 {
48
49 /* ====================================================================== */
50 /* input matrix A definition */
51 /* ====================================================================== */
52
53 int A [ALEN] = {
54
55 0, 1, 4, /* row indices of nonzeros in column 0 */
56 2, 4, /* row indices of nonzeros in column 1 */
57 0, 1, 2, 3, /* row indices of nonzeros in column 2 */
58 1, 3} ; /* row indices of nonzeros in column 3 */
59
60 int p [ ] = {
61
62 0, /* column 0 is in A [0..2] */
63 3, /* column 1 is in A [3..4] */
64 5, /* column 2 is in A [5..8] */
65 9, /* column 3 is in A [9..10] */
66 A_NNZ} ; /* number of nonzeros in A */
67
68 /* ====================================================================== */
69 /* input matrix B definition */
70 /* ====================================================================== */
71
72 int B [ ] = { /* Note: only strictly lower triangular part */
73 /* is included, since symamd ignores the */
74 /* diagonal and upper triangular part of B. */
75
76 1, /* row indices of nonzeros in column 0 */
77 2, 3, /* row indices of nonzeros in column 1 */
78 /* row indices of nonzeros in column 2 (none) */
79 4 /* row indices of nonzeros in column 3 */
80 } ; /* row indices of nonzeros in column 4 (none) */
81
82 int q [ ] = {
83
84 0, /* column 0 is in B [0] */
85 1, /* column 1 is in B [1..2] */
86 3, /* column 2 is empty */
87 3, /* column 3 is in B [3] */
88 4, /* column 4 is empty */
89 B_NNZ} ; /* number of nonzeros in strictly lower B */
90
91 /* ====================================================================== */
92 /* other variable definitions */
93 /* ====================================================================== */
94
95 int perm [B_N+1] ; /* note the size is N+1 */
96 int stats [COLAMD_STATS] ; /* for colamd and symamd output statistics */
97
98 int row, col, pp, length, ok ;
99
100 /* ====================================================================== */
101 /* dump the input matrix A */
102 /* ====================================================================== */
103
104 printf ("colamd %d-by-%d input matrix:\n", A_NROW, A_NCOL) ;
105 for (col = 0 ; col < A_NCOL ; col++)
106 {
107 length = p [col+1] - p [col] ;
108 printf ("Column %d, with %d entries:\n", col, length) ;
109 for (pp = p [col] ; pp < p [col+1] ; pp++)
110 {
111 row = A [pp] ;
112 printf (" row %d\n", row) ;
113 }
114 }
115
116 /* ====================================================================== */
117 /* order the matrix. Note that this destroys A and overwrites p */
118 /* ====================================================================== */
119
120 ok = colamd (A_NROW, A_NCOL, ALEN, A, p, (double *) NULL, stats) ;
121 colamd_report (stats) ;
122
123 if (!ok)
124 {
125 printf ("colamd error!\n") ;
126 exit (1) ;
127 }
128
129 /* ====================================================================== */
130 /* print the column ordering */
131 /* ====================================================================== */
132
133 printf ("colamd column ordering:\n") ;
134 printf ("1st column: %d\n", p [0]) ;
135 printf ("2nd column: %d\n", p [1]) ;
136 printf ("3rd column: %d\n", p [2]) ;
137 printf ("4th column: %d\n", p [3]) ;
138
139 /* ====================================================================== */
140 /* dump the strictly lower triangular part of symmetric input matrix B */
141 /* ====================================================================== */
142
143 printf ("\n\nsymamd %d-by-%d input matrix:\n", B_N, B_N) ;
144 printf ("Entries in strictly lower triangular part:\n") ;
145 for (col = 0 ; col < B_N ; col++)
146 {
147 length = q [col+1] - q [col] ;
148 printf ("Column %d, with %d entries:\n", col, length) ;
149 for (pp = q [col] ; pp < q [col+1] ; pp++)
150 {
151 row = B [pp] ;
152 printf (" row %d\n", row) ;
153 }
154 }
155
156 /* ====================================================================== */
157 /* order the matrix B. Note that this does not modify B or q. */
158 /* ====================================================================== */
159
160 ok = symamd (B_N, B, q, perm, (double *) NULL, stats, &calloc, &free) ;
161 symamd_report (stats) ;
162
163 if (!ok)
164 {
165 printf ("symamd error!\n") ;
166 exit (1) ;
167 }
168
169 /* ====================================================================== */
170 /* print the symmetric ordering */
171 /* ====================================================================== */
172
173 printf ("symamd column ordering:\n") ;
174 printf ("1st row/column: %d\n", perm [0]) ;
175 printf ("2nd row/column: %d\n", perm [1]) ;
176 printf ("3rd row/column: %d\n", perm [2]) ;
177 printf ("4th row/column: %d\n", perm [3]) ;
178 printf ("5th row/column: %d\n", perm [4]) ;
179
180 exit (0) ;
181 }
182