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# 矩阵排名程序 > 原文: [https://www.geeksforgeeks.org/program-for-rank-of-matrix/](https://www.geeksforgeeks.org/program-for-rank-of-matrix/) **矩阵的秩是多少?** 大小为 M x N 的矩阵 A 的秩定义为 。(a)矩阵中或 HTHT4 中线性独立列向量的最大数量。 矩阵。 [](https://practice.geeksforgeeks.org/problem-page.php?pid=332) ## 强烈建议您在继续解决方案之前,单击此处进行练习。 示例: ``` Input: mat[][] = {{10, 20, 10}, {20, 40, 20}, {30, 50, 0}} Output: Rank is 2 Explanation: Ist and IInd rows are linearly dependent. But Ist and 3rd or IInd and IIIrd are independent. Input: mat[][] = {{10, 20, 10}, {-20, -30, 10}, {30, 50, 0}} Output: Rank is 2 Explanation: Ist and IInd rows are linearly independent. So rank must be atleast 2\. But all three rows are linearly dependent (the first is equal to the sum of the second and third) so the rank must be less than 3\. ``` 换句话说,A 的秩是 A 中任何非零未成年人的最大阶,其中次幂的阶次是确定它的平方子矩阵的边长。 因此,如果 M < N,则 A 的最大秩可以为 M,否则可以为 N,通常矩阵的秩不能大于 min(M,N)。 仅当矩阵不包含非零元素时,矩阵的秩才会为零。 如果矩阵甚至具有一个非零元素,则其最小秩为 1。 **如何找到排名?** 这个想法是基于转换为[行梯形表格](https://en.wikipedia.org/wiki/Row_echelon_form)的。 ``` 1) Let the input matrix be mat[][]. Initialize rank equals to number of columns // Before we visit row 'row', traversal of previous // rows make sure that mat[row][0],....mat[row][row-1] // are 0. 2) Do following for row = 0 to rank-1. a) If mat[row][row] is not zero, make all elements of current column as 0 except the element mat[row][row] by finding appropriate multiplier and adding a the multiple of row 'row' b) Else (mat[row][row] is zero). Two cases arise: (i) If there is a row below it with non-zero entry in same column, then swap current 'row' and that row. (ii) If all elements in current column below mat[r][row] are 0, then remove this column by swapping it with last column and reducing number of rank by 1. Reduce row by 1 so that this row is processed again. 3) Number of remaining columns is rank of matrix. ``` 例: ``` Input: mat[][] = {{10, 20, 10}, {-20, -30, 10}, {30, 50, 0}} row = 0: Since mat[0][0] is not 0, we are in case 2.a of above algorithm. We set all entries of 0'th column as 0 (except entry mat[0][0]). To do this, we subtract R1*(-2) from R2, i.e., R2 --> R2 - R1*(-2) mat[][] = {{10, 20, 10}, { 0, 10, 30}, {30, 50, 0}} And subtract R1*3 from R3, i.e., R3 --> R3 - R1*3 mat[][] = {{10, 20, 10}, { 0, 10, 30}, { 0, -10, -30}} row = 1: Since mat[1][1] is not 0, we are in case 2.a of above algorithm. We set all entries of 1st column as 0 (except entry mat[1][1]). To do this, we subtract R2*2 from R1, i.e., R1 --> R1 - R2*2 mat[][] = {{10, 0, -50}, { 0, 10, 30}, { 0, -10, -30}} And subtract R2*(-1) from R3, i.e., R3 --> R3 - R2*(-1) mat[][] = {{10, 0, -50}, { 0, 10, 30}, { 0, 0, 0}} row = 2: Since Since mat[2][2] is 0, we are in case 2.b of above algorithm. Since there is no row below it swap. We reduce the rank by 1 and keep row as 2\. The loop doesn't iterate next time because loop termination condition row <= rank-1 returns false. ``` 以下是上述想法的实现。 ## C++ ```cpp // C++ program to find rank of a matrix #include <bits/stdc++.h> using namespace std; #define R 3 #define C 3 /* function for exchanging two rows of    a matrix */ void swap(int mat[R][C], int row1, int row2,           int col) {     for (int i = 0; i < col; i++)     {         int temp = mat[row1][i];         mat[row1][i] = mat[row2][i];         mat[row2][i] = temp;     } } // Function to display a matrix void display(int mat[R][C], int row, int col); /* function for finding rank of matrix */ int rankOfMatrix(int mat[R][C]) {     int rank = C;     for (int row = 0; row < rank; row++)     {         // Before we visit current row 'row', we make         // sure that mat[row][0],....mat[row][row-1]         // are 0\.         // Diagonal element is not zero         if (mat[row][row])         {            for (int col = 0; col < R; col++)            {                if (col != row)                {                  // This makes all entries of current                  // column as 0 except entry 'mat[row][row]'                  double mult = (double)mat[col][row] /                                        mat[row][row];                  for (int i = 0; i < rank; i++)                    mat[col][i] -= mult * mat[row][i];               }            }         }         // Diagonal element is already zero. Two cases         // arise:         // 1) If there is a row below it with non-zero         //    entry, then swap this row with that row         //    and process that row         // 2) If all elements in current column below         //    mat[r][row] are 0, then remvoe this column         //    by swapping it with last column and         //    reducing number of columns by 1\.         else         {             bool reduce = true;             /* Find the non-zero element in current                 column  */             for (int i = row + 1; i < R;  i++)             {                 // Swap the row with non-zero element                 // with this row.                 if (mat[i][row])                 {                     swap(mat, row, i, rank);                     reduce = false;                     break ;                 }             }             // If we did not find any row with non-zero             // element in current columnm, then all             // values in this column are 0\.             if (reduce)             {                 // Reduce number of columns                 rank--;                 // Copy the last column here                 for (int i = 0; i < R; i ++)                     mat[i][row] = mat[i][rank];             }             // Process this row again             row--;         }        // Uncomment these lines to see intermediate results        // display(mat, R, C);        // printf("\n");     }     return rank; } /* function for displaying the matrix */ void display(int mat[R][C], int row, int col) {     for (int i = 0; i < row; i++)     {         for (int j = 0; j < col; j++)             printf("  %d", mat[i][j]);         printf("\n");     } } // Driver program to test above functions int main() {    int mat[][3] = {{10,   20,   10},                   {-20,  -30,   10},                    {30,   50,   0}};     printf("Rank of the matrix is : %d",          rankOfMatrix(mat));     return 0; } ``` ## Java ```java // Java program to find rank of a matrix class GFG {     static final int R = 3;     static final int C = 3;     // function for exchanging two rows     // of a matrix      static void swap(int mat[][],            int row1, int row2, int col)     {         for (int i = 0; i < col; i++)         {             int temp = mat[row1][i];             mat[row1][i] = mat[row2][i];             mat[row2][i] = temp;         }     }     // Function to display a matrix     static void display(int mat[][],                       int row, int col)     {         for (int i = 0; i < row; i++)         {             for (int j = 0; j < col; j++)                 System.out.print(" "                           + mat[i][j]);             System.out.print("\n");         }     }      // function for finding rank of matrix      static int rankOfMatrix(int mat[][])     {         int rank = C;         for (int row = 0; row < rank; row++)         {             // Before we visit current row              // 'row', we make sure that              // mat[row][0],....mat[row][row-1]             // are 0\.             // Diagonal element is not zero             if (mat[row][row] != 0)             {                 for (int col = 0; col < R; col++)                 {                     if (col != row)                     {                         // This makes all entries                          // of current column                          // as 0 except entry                          // 'mat[row][row]'                         double mult =                             (double)mat[col][row] /                                     mat[row][row];                         for (int i = 0; i < rank; i++)                             mat[col][i] -= mult                                         * mat[row][i];                     }                 }             }             // Diagonal element is already zero.              // Two cases arise:             // 1) If there is a row below it              // with non-zero entry, then swap              // this row with that row and process              // that row             // 2) If all elements in current              // column below mat[r][row] are 0,              // then remvoe this column by              // swapping it with last column and             // reducing number of columns by 1\.             else             {                 boolean reduce = true;                 // Find the non-zero element                  // in current column                  for (int i = row + 1; i < R; i++)                 {                     // Swap the row with non-zero                      // element with this row.                     if (mat[i][row] != 0)                     {                         swap(mat, row, i, rank);                         reduce = false;                         break ;                     }                 }                 // If we did not find any row with                  // non-zero element in current                  // columnm, then all values in                  // this column are 0\.                 if (reduce)                 {                     // Reduce number of columns                     rank--;                     // Copy the last column here                     for (int i = 0; i < R; i ++)                         mat[i][row] = mat[i][rank];                 }                 // Process this row again                 row--;             }         // Uncomment these lines to see          // intermediate results display(mat, R, C);         // printf("\n");         }         return rank;     }     // Driver code     public static void main (String[] args)     {         int mat[][] = {{10, 20, 10},                        {-20, -30, 10},                        {30, 50, 0}};         System.out.print("Rank of the matrix is : "                                 + rankOfMatrix(mat));     } } // This code is contributed by Anant Agarwal. ``` ## Python3 ```py # Python 3 program to find rank of a matrix class rankMatrix(object):     def __init__(self, Matrix):         self.R = len(Matrix)         self.C = len(Matrix[0])     # Function for exchanging two rows of a matrix     def swap(self, Matrix, row1, row2, col):         for i in range(col):             temp = Matrix[row1][i]             Matrix[row1][i] = Matrix[row2][i]             Matrix[row2][i] = temp     # Function to Display a matrix     def Display(self, Matrix, row, col):         for i in range(row):             for j in range(col):                 print (" " + str(Matrix[i][j]))             print ('\n')     # Find rank of a matrix     def rankOfMatrix(self, Matrix):         rank = self.C         for row in range(0, rank, 1):             # Before we visit current row              # 'row', we make sure that              # mat[row][0],....mat[row][row-1]              # are 0.              # Diagonal element is not zero             if Matrix[row][row] != 0:                 for col in range(0, self.R, 1):                     if col != row:                         # This makes all entries of current                          # column as 0 except entry 'mat[row][row]'                          multiplier = (Matrix[col][row] /                                       Matrix[row][row])                         for i in range(rank):                             Matrix[col][i] -= (multiplier *                                                Matrix[row][i])             # Diagonal element is already zero.              # Two cases arise:              # 1) If there is a row below it              # with non-zero entry, then swap              # this row with that row and process              # that row              # 2) If all elements in current              # column below mat[r][row] are 0,              # then remvoe this column by              # swapping it with last column and              # reducing number of columns by 1.              else:                 reduce = True                 # Find the non-zero element                  # in current column                  for i in range(row + 1, self.R, 1):                     # Swap the row with non-zero                      # element with this row.                     if Matrix[i][row] != 0:                         self.swap(Matrix, row, i, rank)                         reduce = False                         break                 # If we did not find any row with                  # non-zero element in current                  # columnm, then all values in                  # this column are 0\.                 if reduce:                     # Reduce number of columns                      rank -= 1                     # copy the last column here                     for i in range(0, self.R, 1):                         Matrix[i][row] = Matrix[i][rank]                 # process this row again                 row -= 1         # self.Display(Matrix, self.R,self.C)          return (rank) # Driver Code if __name__ == '__main__':     Matrix = [[10, 20, 10],               [-20, -30, 10],               [30, 50, 0]]     RankMatrix = rankMatrix(Matrix)     print ("Rank of the Matrix is:",             (RankMatrix.rankOfMatrix(Matrix))) # This code is contributed by Vikas Chitturi  ``` ## C# ```cs // C# program to find rank of a matrix using System; class GFG {     static  int R = 3;     static  int C = 3;     // function for exchanging two rows     // of a matrix      static void swap(int [,]mat,            int row1, int row2, int col)     {         for (int i = 0; i < col; i++)         {             int temp = mat[row1,i];             mat[row1,i] = mat[row2,i];             mat[row2,i] = temp;         }     }     // Function to display a matrix     static void display(int [,]mat,                       int row, int col)     {         for (int i = 0; i < row; i++)         {             for (int j = 0; j < col; j++)                 Console.Write(" "                           + mat[i,j]);             Console.Write("\n");         }     }      // function for finding rank of matrix      static int rankOfMatrix(int [,]mat)     {         int rank = C;         for (int row = 0; row < rank; row++)         {             // Before we visit current row              // 'row', we make sure that              // mat[row][0],....mat[row][row-1]             // are 0\.             // Diagonal element is not zero             if (mat[row,row] != 0)             {                 for (int col = 0; col < R; col++)                 {                     if (col != row)                     {                         // This makes all entries                          // of current column                          // as 0 except entry                          // 'mat[row][row]'                         double mult =                             (double)mat[col,row] /                                     mat[row,row];                         for (int i = 0; i < rank; i++)                             mat[col,i] -= (int) mult                                      * mat[row,i];                     }                 }             }             // Diagonal element is already zero.              // Two cases arise:             // 1) If there is a row below it              // with non-zero entry, then swap              // this row with that row and process              // that row             // 2) If all elements in current              // column below mat[r][row] are 0,              // then remvoe this column by              // swapping it with last column and             // reducing number of columns by 1\.             else             {                 bool reduce = true;                 // Find the non-zero element                  // in current column                  for (int i = row + 1; i < R; i++)                 {                     // Swap the row with non-zero                      // element with this row.                     if (mat[i,row] != 0)                     {                         swap(mat, row, i, rank);                         reduce = false;                         break ;                     }                 }                 // If we did not find any row with                  // non-zero element in current                  // columnm, then all values in                  // this column are 0\.                 if (reduce)                 {                     // Reduce number of columns                     rank--;                     // Copy the last column here                     for (int i = 0; i < R; i ++)                         mat[i,row] = mat[i,rank];                 }                 // Process this row again                 row--;             }         // Uncomment these lines to see          // intermediate results display(mat, R, C);         // printf("\n");         }         return rank;     }     // Driver code     public static void Main ()     {         int [,]mat = {{10, 20, 10},                        {-20, -30, 10},                        {30, 50, 0}};         Console.Write("Rank of the matrix is : "                           + rankOfMatrix(mat));     } } // This code is contributed by nitin mittal ``` ## PHP ```php <?php // PHP program to find rank of a matrix $R = 3; $C = 3; /* function for exchanging two rows of a matrix */ function swap(&$mat, $row1, $row2, $col) {     for ($i = 0; $i < $col; $i++)     {         $temp = $mat[$row1][$i];         $mat[$row1][$i] = $mat[$row2][$i];         $mat[$row2][$i] = $temp;     } } /* function for finding rank of matrix */ function rankOfMatrix($mat) {     global $R, $C;     $rank = $C;     for ($row = 0; $row < $rank; $row++)     {         // Before we visit current row 'row', we make         // sure that mat[row][0],....mat[row][row-1]         // are 0\.         // Diagonal element is not zero         if ($mat[$row][$row])         {             for ($col = 0; $col < $R; $col++)             {                 if ($col != $row)                 {                     // This makes all entries of current                     // column as 0 except entry 'mat[row][row]'                     $mult = $mat[$col][$row] / $mat[$row][$row];                     for ($i = 0; $i < $rank; $i++)                         $mat[$col][$i] -= $mult * $mat[$row][$i];                 }             }         }         // Diagonal element is already zero. Two cases         // arise:         // 1) If there is a row below it with non-zero         // entry, then swap this row with that row         // and process that row         // 2) If all elements in current column below         // mat[r][row] are 0, then remvoe this column         // by swapping it with last column and         // reducing number of columns by 1\.         else         {             $reduce = true;             /* Find the non-zero element in current                 column */             for ($i = $row + 1; $i < $R; $i++)             {                 // Swap the row with non-zero element                 // with this row.                 if ($mat[$i][$row])                 {                     swap($mat, $row, $i, $rank);                     $reduce = false;                     break ;                 }             }             // If we did not find any row with non-zero             // element in current columnm, then all             // values in this column are 0\.             if ($reduce)             {                 // Reduce number of columns                 $rank--;                 // Copy the last column here                 for ($i = 0; $i < $R; $i++)                     $mat[$i][$row] = $mat[$i][$rank];             }             // Process this row again             $row--;         }     // Uncomment these lines to see intermediate results     // display(mat, R, C);     // printf("\n");     }     return $rank; } /* function for displaying the matrix */ function display($mat, $row, $col) {     for ($i = 0; $i < $row; $i++)     {         for ($j = 0; $j < $col; $j++)             print(" $mat[$i][$j]");         print("\n");     } } // Driver code $mat = array(array(10, 20, 10),                 array(-20, -30, 10),                 array(30, 50, 0)); print("Rank of the matrix is : ".rankOfMatrix($mat)); // This code is contributed by mits ?> ``` **输出**: ``` Rank of the matrix is : 2 ``` 由于以上等级计算方法涉及浮点运算,因此如果除法超出精度,可能会产生错误的结果。 还有其他方法可以处理 **参考**: [https://en.wikipedia.org/wiki/Rank_%28linear_algebra%29](https://en.wikipedia.org/wiki/Rank_%28linear_algebra%29) 本文由 Utkarsh Trivedi 提供。 如果发现任何不正确的地方,或者想分享有关上述主题的更多信息,请写评论。