Monday, 30 January 2017

Program for Matrix Multiplication in JAVA...

Matrix Multiplication: Here is given a Java Program for Matrix Multiplication also call matrix product. In other words, Let the two matrix to be multiplied be A and B. Let A is an n × m order matrix and B is an m × p order matrix, their matrix product A*B is an n × p order matrix, in which the m entries across the rows of A are multiplied with the m entries down the columns of B.

Steps for Matrix Multiplication in Java:

Step 1: Make sure that the the number of columns in the 1st matrix equals the number of rows in the 2nd matrix.
Step 2: Multiply the elements of each row of the first matrix by the elements of each column in the second matrix.
Step 3: Add the products.




Iteration 1
Multiplication of matrix A’s first row with each element of matrix B’s all columns,
1*1+2*5, 1*2+2*6, 1*3+2*7, 1*4+2*8
Iteration 2
Multiplication of matrix A’s second row with each element of matrix B’s all columns,
3*1+4*5, 3*2+4*6, 3*3+4*7, 3*4+4*8
Iteration 3
Multiplication of matrix A’s third row with each element of matrix B’s all columns,
5*1+6*5, 5*2+6*6, 5*3+6*7, 5*4+6*8
Iteration 4
Add all the multiplication and get the matrix with an order 3*4.

METHOD 1 :-
import java.util.*;
class MatrixMultiplication
{
   public static void main(String args[])
   {
      int a, b, p, q, sum = , i, j, k;
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter the number of rows and columns of first matrix");
      a = sc.nextInt();
      b = sc.nextInt();
      int arr1[][] = new int[a][b];
      System.out.println("Enter the elements of first matrix");
      for ( i = ; i < a ; i++ )
         for ( j = ; j < b ; j++ )
            arr1[i][j] = sc.nextInt();
      System.out.println("Enter the number of rows and columns of second matrix");
      p = sc.nextInt();
      q = sc.nextInt();
      if ( b != p )
         System.out.println("Matrices with entered orders can't be multiplied with each other.");
      else
      {
         int arr2[][] = new int[p][q];
         int mult[][] = new int[a][q];
         System.out.println("Enter the elements of second matrix");
         for ( i = ; i < p ; i++ )
            for ( j = ; j < q ; j++ )
               arr2[i][j] = sc.nextInt();
         for ( i = ; i < a ; i++ )
         {
            for ( j = ; j < q ; j++ )
            {  
               for ( k = ; k < p ; k++ )
               {
                  sum = sum + arr1[i][k]*arr2[k][j];
               }
               mult[i][j] = sum;
               sum = ;
            }
         }
         System.out.println("Product of entered matrices:-");
         for ( i = ; i < a ; i++ )
         {
            for ( j = ; j < q ; j++ )
               System.out.print(multiply[i][j]+"t");
            System.out.print("n");
         }
      }
   }
}

Output 1

matrix-multiplication-method 1

METHOD 2 :-

import java.util.*;
class MatrixMultiplication
{
public static void main(String args[])
{
int i, j, k;
int arr1[][]=new int[3][3];
int arr2[][]=new int[3][3];
int mult[][]=new int[3][3];
System.out.println("Enter the first matrix:");
Scanner sc=new Scanner(System.in);
for(i=;i<3;i++)
{
for(j=;j<3;j++)
{
arr1[i][j]=sc.nextInt();
}
}
System.out.println("Enter the second matrix:");
for(i=;i<3;i++)
{
for(j=;j<3;j++)
{
arr2[i][j]=sc.nextInt();
}
}
System.out.println("Matrix multiplication is as follows:");
for(i=;i<3;i++)
{
for(j=;j<3;j++)
{
mult[i][j]=;
for(k=;k<3;k++)
{
   mult[i][j]+=arr1[i][k]*arr2[k][j];
           }
}
     }
     for(i=;i<3;i++)
{
for(j=;j<3;j++)
{
     System.out.print(arr1[i][j]+"t");
     }
System.out.println("n");
         }
         System.out.println("n");
         for(i=;i<3;i++)
{
for(j=;j<3;j++)
{
     System.out.print(arr2[i][j]+"t");
     }
     System.out.println("n");
         }
         System.out.println("n");
     for(i=;i<3;i++)
{
for(j=;j<3;j++)
{
     System.out.print(mult[i][j]+"t");
     }
     System.out.println("n");
         }   
}
}

 Output:
Enter the first matrix:
1 2 3 4 5 6 7 8 9
Enter the second matrix:
9 8 7 6 5 4 3 2 1
Matrix multiplication is as follows:
1 2 3
4 5 6
7 8 9
9 8 7
6 5 4
3 2 1
30 24 18
84 69 54
138 114 90



METHOD 3 :-
import java.util.*;
class MatrixMultiplication
{
    void printMatrix(int arr[][], int m, int n) // Funtion for printing an array
    {
        for(int i=; i<m; i++)
        {
            for(int j=; j<n; j++)
            {
                System.out.print(arr[i][j]+"t");
            }
            System.out.println();
        }
    }
    
    public static void main(String args[])throws Exception
    {
        MatrixMultiplication ob = new MatrixMultiplication();
        Scanner sc = new Scanner(System.in);
        
        System.out.print("Enter no. of rows of 1st Matrix : ");
        int m1=sc.nextInt();
        System.out.print("Enter no. of columns of 1st Matrix : ");
        int n1=sc.nextInt();
        
        System.out.print("Enter no. of rows of 2nd Matrix : ");
        int m2=sc.nextInt();
        System.out.print("Enter no. of columns of 2nd Matrix : ");
        int n2=sc.nextInt();
        
        if(n1 != m2) // check Condition for Multiplication to be possible
        {
            System.out.println("Matrix Multiplication of the given order is not possible");
        }
        else
        {
            int arr1[][]=new int[m1][n1]; // Array to store 1st Matrix
            int arr2[][]=new int[m2][n2]; // Array to store 2nd Matrix
            int mult[][]=new int[m1][n2]; // Array for store Result of matrix Multiplication
            System.out.println("Inputting the 1st Matrix");
            for(int i=; i<m1; i++) //get input of 1st matrix
            {
                for(int j=; j<n1; j++)
                {
                    System.out.print("Enter an element : ");
                    arr1[i][j]=sc.nextInt();
                }
            }
            System.out.println("Inputting the 2nd Matrix");
            for(int i=; i<m2; i++) //get input of 2nd matrix
            {
                for(int j=; j<n2; j++)
                {
                    System.out.print("Enter an element : ");
                    arr2[i][j]=sc.nextInt();
                }
            }
            int s = ; // initially value of sum=0
            for(int i=; i<m1; i++) //multiplication of matrix start here
            {
                for(int j=; j<n2; j++)
                {
                    for(int k=; k<n1; k++)
                    {
                        s = s + arr1[i][k]*arr2[k][j];
                    }
                    mult[i][j]=s;
                    s=;
                }
            }
            
            /* Print all the Matrix */
            System.out.println("          Output         ");
            System.out.println("The 1st Matrix is");
            ob.printMatrix(arr1,m1,n1);
            System.out.println("The 2nd Matrix is");
            ob.printMatrix(arr2,m2,n2);
            System.out.println("The Result of Multiplication is");
            ob.printMatrix(mult,m1,n2);
        }
    }
}


  • Output:
    Enter no. of rows of 1st Matrix : 3
    Enter no. of columns of 1st Matrix : 2
    Enter no. of rows of 2nd Matrix : 2
    Enter no. of columns of 2nd Matrix : 4
    Inputting the 1st Matrix
    Enter an element : 1
    Enter an element : 4
    Enter an element : 8
    Enter an element : 2
    Enter an element : 3
    Enter an element : 6
    Inputting the 2nd Matrix
    Enter an element : 5
    Enter an element : 2
    Enter an element : 3
    Enter an element : 1
    Enter an element : 4
    Enter an element : 5
    Enter an element : 6
    Enter an element : 8
    Output
    The 1st Matrix is
    1 4
    8 2
    3 6
    The 2nd Matrix is
    5 2 3 1
    4 5 6 8
    The Result of Matrix Multiplication is
    21 22 27 33
    48 26 36 24
    39 36 45 51



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