Vector multiplication A and B resulting in matrix C

Question

I have an exercise in Java here to solve but I could not understand exactly what I need to do, if anyone can give me a better explanation thank you! This is what I need to do:

Given the vectors A = [1,2,3,4,5] and B = [1,2,3,4,5], create algorithms to generate a matrix C of the multiplication of the elements of A by the elements of B. Note that

C[1,1] <- A[1,1] * B[1,1]
C[1,2] <- A[1,1] * B[1,2]
C[1,3] <- A[1,1] * B[1,3] 
...

Answer 1

You need to use two interleaved loops to do this type of operation: the outermost one will fill rows of the resulting matrix, while moving the items of the first array(Veta), the second one will fill columns of the resulting matrix, while moving items of the second array(vetB):

The code stays that way:

int[] vetA = {1,2,3,4,5};
int[] vetB = {1,2,3,4,5};
int[][] mat =  new int[5][5];

for(int i = 0; i < vetA.length;i++){
    for(int j = 0; j < vetB.length; j++){
        mat[i][j] = vetA[i] * vetB[j];
    }
}

for(int i = 0; i < mat[0].length; i++){
    for(int j = 0; j < mat.length;j++ ){
        System.out.print(mat[i][j] + " ");
    }
    System.out.println();
}

Upshot:

1 2 3 4 5 
2 4 6 8 10 
3 6 9 12 15 
4 8 12 16 20 
5 10 15 20 25

See it working on ideone: https://ideone.com/Qp7iYG

Note that as we have a multiplication that will result in a square matrix, you can use the same combination to display on the screen.