回答編集履歴
2
微修正
answer
CHANGED
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@@ -4,7 +4,7 @@
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4
4
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```C
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5
5
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#include <stdio.h>
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6
6
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7
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-
#define at(t,
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7
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+
#define at(t,y,x) t[y*4+x]
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8
8
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9
9
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int main() {
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10
10
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float a[16] = {
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1
追記
answer
CHANGED
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@@ -1,1 +1,45 @@
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1
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-
簡単もなにもベクトルの内積を4x4回繰り返す以外なんかあるん?
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1
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+
簡単もなにもベクトルの内積を4x4回繰り返す以外なんかあるん?
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2
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+
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3
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+
[追記] 愚直な実装でよければ:
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4
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+
```C
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5
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+
#include <stdio.h>
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6
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+
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7
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+
#define at(t,x,y) t[y*4+x]
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8
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+
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9
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+
int main() {
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10
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float a[16] = {
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11
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+
1.000000,0.000000,0.000000,0.000000,
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12
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0.000000,1.000000,0.000000,0.000000,
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13
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0.000000,0.000000,1.000000,0.000000,
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14
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0.000000,0.000000,0.000000,1.000000 };
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15
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+
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16
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float b[16] = {
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17
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1.000000,0.000000,0.000000,0.000000,
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18
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+
0.000000,1.000000,0.000000,0.000000,
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19
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0.000000,0.000000,1.000000,0.000000,
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20
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0.000000,0.000000,0.000000,1.000000 };
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21
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+
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22
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+
float c[16];
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23
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+
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24
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int row, col;
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25
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for ( row = 0; row < 4; ++row ) {
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26
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+
for ( col =0; col < 4; ++col ) {
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27
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float sum = 0.0f;
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28
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int t;
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29
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for ( t = 0; t <4; ++t ) {
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30
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sum += at(a,row,t) * at(b,t,col);
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31
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}
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32
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at(c,row,col) = sum;
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33
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}
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34
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}
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35
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+
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36
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// できたかな?
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37
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for ( row = 0; row < 4; ++row) {
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38
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for ( col = 0; col < 4; ++col) {
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39
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printf("%f ", at(c,row,col));
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40
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}
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41
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puts("");
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42
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}
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43
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return 0;
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44
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+
}
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45
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+
```
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