回答編集履歴
2
修正
test
CHANGED
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@@ -68,7 +68,7 @@
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68
68
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69
69
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i = 0;
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70
70
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71
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-
d
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71
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d = a[i][3] / a[i][i];
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72
72
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73
73
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j = 1; a[i][N] = d - a[i][j]*a[j][N]/a[i][i];
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74
74
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1
追記
test
CHANGED
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@@ -21,3 +21,63 @@
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21
21
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`(x+y+z) / w = x/w + y/w + z/w`
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22
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23
23
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という展開は無駄でしかない
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24
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25
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26
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27
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---
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28
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29
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30
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31
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**追記**
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32
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33
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34
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35
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とりあえず、前回の計算式
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36
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37
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`a[i][N] = (a[i][N]-なにか) / a[i][i]`を思い出す。
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38
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39
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分配する
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40
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41
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`a[i][N] = a[i][N]/a[i][i] - なにか/a[i][i]`
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42
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43
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あとはそれに従ってプログラムに変換するだけ
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44
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45
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46
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47
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---
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48
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49
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50
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51
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> for (i = N - 1; i >= 0; i--) {
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52
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53
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> d = a[i][N]/ a[i][i];
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54
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55
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> for (j = i + 1; j < N; j++)
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56
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57
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> a[i][N] = d- a[i][j] * a[j][N] / a[i][i];
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58
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59
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> }
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60
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61
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62
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63
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このfor文をi=0,N=3で展開すると
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64
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65
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66
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67
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```c
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68
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69
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i = 0;
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70
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71
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double d = a[i][3] / a[i][i];
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72
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73
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j = 1; a[i][N] = d - a[i][j]*a[j][N]/a[i][i];
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74
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75
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j = 2; a[i][N] = d - a[i][j]*a[j][N]/a[i][i];
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76
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77
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```
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78
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79
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80
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81
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みたいな感じ
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82
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83
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`j=1`の時の計算が丸ごと捨てられています。
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