C++ 語言編寫程式,檢查冪等矩陣
假設 M[r][c] 是一個矩陣,“r”表示行數,“c”表示列數,其中 r = c 表示一個方陣。我們要檢查給定的方陣是不是一個冪等矩陣。
冪等矩陣
如果並且僅當矩陣“M”與自身相乘等於“M”,則矩陣“M”被稱為冪等矩陣,即 M * M = M.
比如以下示例 −
我們可以說,上述矩陣與自身相乘等於自身,因此該矩陣是冪等矩陣。
示例
Input: m[3][3] = { {2, -2, -4}, {-1, 3, 4}, {1, -2, -3}} Output: Idempotent Input: m[3][3] == { {3, 0, 0}, {0, 2, 0}, {0, 0, 3} } Output: Not Idempotent
演算法
Start Step 1 -> define macro as #define size 3 Step 2 -> declare function for matrix multiplication void multiply(int arr[][size], int res[][size]) Loop For int i = 0 and i < size and i++ Loop For int j = 0 and j < size and j++ Set res[i][j] = 0 Loop for int k = 0 and k < size and k++ Set res[i][j] += arr[i][k] * arr[k][j] End End End Step 3 -> declare function to check idempotent or not bool check(int arr[][size]) declare int res[size][size] call multiply(arr, res) Loop For int i = 0 and i < size and i++ Loop For int j = 0 and j < size and j++ IF (arr[i][j] != res[i][j]) return false End End End return true step 4 -> In main() declare int arr[size][size] = {{1, -1, -1}, {-1, 1, 1}, {1, -1, -1}} IF (check(arr)) Print its an idempotent matrix Else Print its not an idempotent matrix Stop
示例
#include<bits/stdc++.h> #define size 3 using namespace std; //matrix multiplication. void multiply(int arr[][size], int res[][size]){ for (int i = 0; i < size; i++){ for (int j = 0; j < size; j++){ res[i][j] = 0; for (int k = 0; k < size; k++) res[i][j] += arr[i][k] * arr[k][j]; } } } //check idempotent or not bool check(int arr[][size]){ int res[size][size]; multiply(arr, res); for (int i = 0; i < size; i++) for (int j = 0; j < size; j++) if (arr[i][j] != res[i][j]) return false; return true; } int main(){ int arr[size][size] = {{1, -1, -1}, {-1, 1, 1}, {1, -1, -1}}; if (check(arr)) cout << "its an idempotent matrix"; else cout << "its not an idempotent matrix"; return 0; }
輸出
its an idempotent matrix
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