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1 | /* -*-c-*- |
2 | * | |
05dfc037 | 3 | * $Id$ |
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4 | * |
5 | * Matrix arithmetic mod %$2^{24}$% | |
6 | * | |
7 | * (c) 2000 Mark Wooding | |
8 | */ | |
9 | ||
10 | /*----- Licensing notice --------------------------------------------------* | |
11 | * | |
12 | * Copyright (c) 2000 Mark Wooding | |
13 | * All rights reserved. | |
14 | * | |
15 | * Redistribution and use in source and binary forms, with or without | |
16 | * modification, are permitted provided that the following conditions are | |
17 | * met: | |
18 | * | |
19 | * 1. Redistributions of source code must retain the above copyright | |
20 | * notice, this list of conditions and the following disclaimer. | |
21 | * | |
22 | * 2, Redistributions in binary form must reproduce the above copyright | |
23 | * notice, this list of conditions and the following disclaimer in the | |
24 | * documentation and/or other materials provided with the distribution. | |
25 | * | |
26 | * 3. The name of the authors may not be used to endorse or promote | |
27 | * products derived from this software without specific prior written | |
28 | * permission. | |
29 | * | |
30 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
31 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF | |
32 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN | |
02f1f6b7 | 33 | * NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
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34 | * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
35 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
36 | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
37 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
38 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN | |
39 | * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
40 | * POSSIBILITY OF SUCH DAMAGE. | |
41 | * | |
42 | * Instead of accepting the above terms, you may redistribute and/or modify | |
43 | * this software under the terms of either the GNU General Public License, | |
44 | * or the GNU Library General Public License, published by the Free | |
45 | * Software Foundation; either version 2 of the License, or (at your | |
46 | * option) any later version. | |
47 | */ | |
48 | ||
49 | /*----- Revision history --------------------------------------------------* | |
50 | * | |
51 | * $Log: matrix.c,v $ | |
da124bf5 MW |
52 | * Revision 1.3 2000/08/05 11:27:56 mdw |
53 | * (matinv): Fix type error. | |
54 | * | |
02f1f6b7 MW |
55 | * Revision 1.2 2000/07/02 15:22:07 mdw |
56 | * Fix licence text. Change to matinv to mark inputs as constants. | |
57 | * | |
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58 | * Revision 1.1 2000/05/21 11:28:30 mdw |
59 | * Initial check-in. | |
60 | * | |
61 | */ | |
62 | ||
63 | /*----- Header files ------------------------------------------------------*/ | |
64 | ||
65 | #include <assert.h> | |
66 | #include <stdio.h> | |
67 | #include <stdlib.h> | |
68 | ||
69 | #include "arith24.h" | |
70 | #include "bits.h" | |
71 | #include "matrix.h" | |
72 | ||
73 | /*----- Main code ---------------------------------------------------------*/ | |
74 | ||
75 | /* --- @matmul@ --- * | |
76 | * | |
77 | * Arguments: @uint24 *d@ = pointer to destination matrix | |
78 | * @uint24 *a, *b@ = pointer to operand matrices | |
79 | * @unsigned x, y, z@ = dimensions of the operand matrices | |
80 | * | |
81 | * Returns: --- | |
82 | * | |
83 | * Use: Performs matrix multiplication mod %$2^{24}$%. The matrix | |
84 | * @d@ may not overlap either operand matrix. | |
85 | */ | |
86 | ||
87 | void matmul(uint24 *d, const uint24 *a, const uint24 *b, | |
88 | unsigned x, unsigned y, unsigned z) | |
89 | { | |
90 | unsigned i, j, k; | |
91 | ||
92 | for (i = 0; i < x; i++) { | |
93 | const uint24 *bb = b; | |
94 | for (j = 0; j < z; j++) { | |
95 | uint24 n = 0; | |
96 | for (k = 0; k < y; k++) | |
97 | n += a[k] * bb[k * z]; | |
98 | *d++ = U24(n); | |
99 | bb++; | |
100 | } | |
101 | a += y; | |
102 | } | |
103 | } | |
104 | ||
105 | /* --- @matinv@ --- * | |
106 | * | |
107 | * Arguments: @uint24 *d@ = pointer to destination matrix | |
02f1f6b7 | 108 | * @const uint24 *a@ = pointer to operand matrix |
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109 | * @unsigned x, y@ = dimensions of operand matrix |
110 | * | |
111 | * Returns: Zero if the matrix was successfully inverted, %$-1$% if the | |
112 | * matrix is singular. | |
113 | * | |
114 | * Use: Computes the mod %$2^{24}$% inverse of a square matrix. | |
115 | */ | |
116 | ||
02f1f6b7 | 117 | int matinv(uint24 *d, const uint24 *a, unsigned x, unsigned y) |
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118 | { |
119 | unsigned i, j, k; | |
120 | uint24 *aa; | |
da124bf5 | 121 | uint24 *p, *q, *r, *s; |
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122 | |
123 | assert(x == y); | |
124 | ||
125 | aa = malloc(sizeof(uint24) * x * y); | |
126 | if (!aa) { | |
127 | fprintf(stderr, "unable to allocate memory\n"); | |
128 | exit(EXIT_FAILURE); | |
129 | } | |
130 | memcpy(aa, a, sizeof(uint24) * x * y); | |
131 | ||
132 | p = d; | |
133 | for (i = 0; i < x; i++) { | |
134 | for (j = 0; j < y; j++) | |
135 | *p++ = i == j; | |
136 | } | |
137 | ||
138 | for (i = 0; i < x; i++) { | |
139 | uint24 c = inv24(aa[(x + 1) * i]); | |
140 | if (!c) | |
141 | goto fail; | |
142 | r = aa + y * i; | |
143 | s = d + y * i; | |
144 | for (j = 0; j < y; j++) { | |
145 | r[j] = U24(r[j] * c); | |
146 | s[j] = U24(s[j] * c); | |
147 | } | |
148 | for (j = 0; j < x; j++) { | |
149 | if (j == i) | |
150 | continue; | |
151 | p = aa + y * j; | |
152 | q = d + y * j; | |
153 | c = p[i]; | |
154 | for (k = 0; k < y; k++) { | |
155 | p[k] = U24(p[k] - c * r[k]); | |
156 | q[k] = U24(q[k] - c * s[k]); | |
157 | } | |
158 | } | |
159 | } | |
160 | ||
161 | free(aa); | |
162 | return (0); | |
163 | ||
164 | fail: | |
165 | free(aa); | |
166 | return (-1); | |
167 | } | |
168 | ||
169 | /*----- That's all, folks -------------------------------------------------*/ |