don’t know where to start someone to help me?

Question

Read two integer matrices A and B (5 X 5) and, from them, manages the SOMA matrix (corresponding to the sum of the two matrices: A + B) and the matrix SUBTRACTION (corresponding to subtraction between the two matrices: A - B).

What I’ve done so far is:

var matrizA= [
  [],[],[],[],[],
  [],[],[],[],[],
  [],[],[],[],[],
  [],[],[],[],[],
  [],[],[],[],[] 
];
var matrizB=[ 
  [],[],[],[],[],
  [],[],[],[],[],
  [],[],[],[],[],
  [],[],[],[],[],
  [],[],[],[],[] 
];
for (var linha = 0; linha <= 4; linha++) {
  matrizA = prompt("digite 5 valores para matrizA: ");
  matrizB = prompt("digite 5 valores para matrizB: ")
  for (var coluna = 0; coluna <= 4; coluna++) {
    matrizA[linha][coluna] = matrizB[linha][coluna] = (linha + 1) + (coluna + 1);
    document.write("[" + (linha + 1) + "] + [" + (coluna + 1) + "] =" + matrizA[linha][coluna] + matrizB[linha][coluna] + "<br>");
  }
  document.write("<br>");
}

Answer 1

I read that question like this:

Create two arrays, with integer numbers.
Then generates a new matrix where each position contains the sum of the respective numbers in the other matrices.
Then generates a new matrix where each position contains the sum of the respective numbers in the other matrices.

I don’t know how you want to add these numbers, but in case you already have them, you can create new arrays with the .map() because what you want are new arrays with the same structure but with the sums/subtractions...

An example would be:

const a = [
  [1, 2, 3, 4, 5],
  [1, 2, 3, 4, 5],
  [6, 7, 8, 9, 0],
  [1, 2, 3, 4, 5],
  [1, 2, 3, 4, 5]
]

const b = [
  [6, 7, 8, 9, 10],
  [6, 7, 8, 9, 0],
  [1, 2, 3, 4, 5],
  [6, 7, 8, 9, 10],
  [6, 7, 8, 9, 0],
]

const AmenosB = a.map((arraydeCinco, i) => {
  return arraydeCinco.map((numero, x) => {
    return numero - b[i][x];
  });
});
const AmaisB = a.map((arraydeCinco, i) => {
  return arraydeCinco.map((numero, x) => {
    return numero + b[i][x];
  });
});

console.log('AmenosB', JSON.stringify(AmenosB));
console.log('AmaisB', JSON.stringify(AmaisB));

Since you have a lot of duplicate code you can simplify it like this:

const a = [
  [1, 2, 3, 4, 5],
  [1, 2, 3, 4, 5],
  [6, 7, 8, 9, 0],
  [1, 2, 3, 4, 5],
  [1, 2, 3, 4, 5]
]

const b = [
  [6, 7, 8, 9, 10],
  [6, 7, 8, 9, 0],
  [1, 2, 3, 4, 5],
  [6, 7, 8, 9, 10],
  [6, 7, 8, 9, 0],
]


const calc = (arrA, arrB, sign) => {
  return arrA.map((arr, i) => {
    return arr.map((numero, x) => {
      return numero + (arrB[i][x] * sign);
    });
  });
}

const AmenosB = calc(a, b, -1);
const AmaisB = calc(a, b, 1);


console.log('AmenosB', JSON.stringify(AmenosB));
console.log('AmaisB', JSON.stringify(AmaisB));

The same example with a for could be:

const a = [
  [1, 2, 3, 4, 5],
  [1, 2, 3, 4, 5],
  [6, 7, 8, 9, 0],
  [1, 2, 3, 4, 5],
  [1, 2, 3, 4, 5]
]

const b = [
  [6, 7, 8, 9, 10],
  [6, 7, 8, 9, 0],
  [1, 2, 3, 4, 5],
  [6, 7, 8, 9, 10],
  [6, 7, 8, 9, 0],
]

const AmenosB = [];
const AmaisB = [];
for (let x = 0, lx = a.length; x < lx; x++) {
  const soma = [];
  const diff = [];
  for (let y = 0, ly = a[x].length; y < ly; y++) {
    soma.push(a[x][y] + b[x][y]);
    diff.push(a[x][y] - b[x][y]);
  }
  AmenosB.push(diff);
  AmaisB.push(soma);
}

console.log('AmenosB', JSON.stringify(AmenosB));
console.log('AmaisB', JSON.stringify(AmaisB));