2d matrix multiplication

1double[][] c = new double[N][N];
2for (int i = 0; i < N; i++)
3{
4 for (int j = 0; j < N; j++)
5 	{
6 for (int k = 0; k < N; k++)
7 		{
8		 c[i][j] += a[i][k] * b[k][j];
9 		}
10 	}
11}
12

1#include <stdio.h>
2
3// function to get matrix elements entered by the user
4void getMatrixElements(int matrix[][10], int row, int column) {
5
6   printf("\nEnter elements: \n");
7
8   for (int i = 0; i < row; ++i) {
9      for (int j = 0; j < column; ++j) {
10         printf("Enter a%d%d: ", i + 1, j + 1);
11         scanf("%d", &matrix[i][j]);
12      }
13   }
14}
15
16// function to multiply two matrices
17void multiplyMatrices(int first[][10],
18                      int second[][10],
19                      int result[][10],
20                      int r1, int c1, int r2, int c2) {
21
22   // Initializing elements of matrix mult to 0.
23   for (int i = 0; i < r1; ++i) {
24      for (int j = 0; j < c2; ++j) {
25         result[i][j] = 0;
26      }
27   }
28
29   // Multiplying first and second matrices and storing it in result
30   for (int i = 0; i < r1; ++i) {
31      for (int j = 0; j < c2; ++j) {
32         for (int k = 0; k < c1; ++k) {
33            result[i][j] += first[i][k] * second[k][j];
34         }
35      }
36   }
37}
38
39// function to display the matrix
40void display(int result[][10], int row, int column) {
41
42   printf("\nOutput Matrix:\n");
43   for (int i = 0; i < row; ++i) {
44      for (int j = 0; j < column; ++j) {
45         printf("%d  ", result[i][j]);
46         if (j == column - 1)
47            printf("\n");
48      }
49   }
50}
51
52int main() {
53   int first[10][10], second[10][10], result[10][10], r1, c1, r2, c2;
54   printf("Enter rows and column for the first matrix: ");
55   scanf("%d %d", &r1, &c1);
56   printf("Enter rows and column for the second matrix: ");
57   scanf("%d %d", &r2, &c2);
58
59   // Taking input until
60   // 1st matrix columns is not equal to 2nd matrix row
61   while (c1 != r2) {
62      printf("Error! Enter rows and columns again.\n");
63      printf("Enter rows and columns for the first matrix: ");
64      scanf("%d%d", &r1, &c1);
65      printf("Enter rows and columns for the second matrix: ");
66      scanf("%d%d", &r2, &c2);
67   }
68
69   // get elements of the first matrix
70   getMatrixElements(first, r1, c1);
71
72   // get elements of the second matrix
73   getMatrixElements(second, r2, c2);
74
75   // multiply two matrices.
76   multiplyMatrices(first, second, result, r1, c1, r2, c2);
77
78   // display the result
79   display(result, r1, c2);
80
81   return 0;
82}

1import java.util.Arrays;
2import java.util.Scanner;
3public class Matrix {
4
5    private static int counter =0;
6    private static Scanner scanner = new Scanner(System.in);
7    private int rawForArr1 =0 , columnForArr1=0, rawForArr2=0, ColumnForArr2=0;
8
9    public Matrix(){
10    }
11
12    public Matrix(int rawForArr1, int columnForArr1, int rawForArr2, int columnForArr2) {
13        this.rawForArr1 = rawForArr1;
14        this.columnForArr1 = columnForArr1;
15        this.rawForArr2 = rawForArr2;
16        ColumnForArr2 = columnForArr2;
17    }
18
19    public void sizeOfRawsAndColumns(int r1, int c1, int r2, int c2){
20        System.out.println("Enter numbers of raws for array#1");
21        r1=scanner.nextInt();
22        this.rawForArr1 =r1;
23        System.out.println("Enter numbers of columns for array#1");
24        c1=scanner.nextInt();
25        this.columnForArr1=c1;
26        System.out.println("Enter numbers of raws for array#2");
27        r2=scanner.nextInt();
28        this.rawForArr2 = r2;
29        System.out.println("Enter numbers of columns for array#2");
30        c2=scanner.nextInt();
31        this.ColumnForArr2 = c2;
32        checkIfMatrixIsValid(c1,r2,r1,c2);
33    }
34    public static void printValue(int[][] arr)
35    {
36                System.out.print(Arrays.deepToString(arr));
37    }
38
39    public static void checkIfMatrixIsValid(int c1,int r2,int r1, int c2)
40    {
41        while(c1 != r2)
42        {
43            System.out.println("The columns in the left array is not equal to the raw's in the right"+"\n"+
44                    "array enter other values"+"\n"+
45                    "enter a value and it will be assigned for valid Matrix");
46            Scanner scanner = new Scanner(System.in);
47            c1 = scanner.nextInt();
48            r2 = c1;
49        }
50        int [][] firstArr = initilizeMatrix(r1,c1);
51        int [][] secondArr = initilizeMatrix(r2,c2);
52        EnterElements(firstArr);
53        EnterElements(secondArr);
54        int[][] multplied =multiplieMatrix(firstArr,secondArr);
55        printValue(multplied);
56
57
58
59    }
60
61    public static int [][] initilizeMatrix(int n , int m)
62    {
63
64        int [][] newMatrix = new int[m][n];
65        return  newMatrix;
66
67    }
68
69    public static int [][] multiplieMatrix(int [][] leftArr,int[][] rightArr){
70        int m = leftArr[0].length;
71        int n = rightArr.length;
72        int [][] sumOfMultiplie = new int[m][n];
73        int i=0,j=0,k=0;
74        int sum = 0 ;
75        for( i = 0 ; i < leftArr.length ; ++i)
76        {
77            for(j = 0 ; j < rightArr.length ; ++j)
78            {
79                for(k = 0 ; k < rightArr[0].length ; ++k)
80                {
81                    sum+= leftArr[i][k]*rightArr[k][j];
82                }
83                sumOfMultiplie[i][j]=sum ;
84                sum=0;
85            }
86        }
87        return sumOfMultiplie ;
88    }
89
90    public static int[][] EnterElements(int[][] arr)
91    {
92
93        ++counter;
94        if(counter==1){
95            System.out.println("Enter the elements for the left array"+'\n');
96        }else{
97            System.out.println("Enter the elements for the right array");
98        }
99
100        for(int i = 0 ; i < arr.length ; ++i)
101        {
102            for(int j = 0 ; j<arr.length ; ++j)
103            {
104                System.out.println("Enter element in raw #"+(i+1)+" column #"+(j+1));
105                arr[i][j] = scanner.nextInt();
106            }
107        }
108        return arr ;
109
110    }
111
112
113
114}