// Multiply rows of A by columns of B.
// Print a 2D array (matrix)
function printMatrix(arr2d) {
for (let i = 0; i < arr2d.length; i++) {
let row = "";
for (let j = 0; j < arr2d[i].length; j++) {
row += arr2d[i][j].toString().padStart(4, " ");
}
console.log(row);
}
}
// Multiply matrices A and B into C
function multipleMatrix(a, b, c) {
for (let i = 0; i < c.length; i++) {
for (let j = 0; j < c[i].length; j++) {
for (let k = 0; k < a[i].length; k++) {
c[i][j] += a[i][k] * b[k][j];
}
}
}
}
// Create matrices
const a = [
[1, 8, 5],
[6, 7, 1],
[8, 7, 6]
];
const b = [
[4, 8, 1],
[6, 5, 3],
[4, 6, 5]
];
// Initialize result matrix C with zeros
const c = Array.from({ length: a.length }, () =>
Array(b[0].length).fill(0)
);
// c[0, 0] = (a[0, 0] * b[0, 0]) + (a[0, 1] * b[1, 0]) + (a[0, 2] * b[2, 0])
printMatrix(a);
console.log();
printMatrix(b);
console.log();
multipleMatrix(a, b, c);
printMatrix(c);
/*
run:
1 8 5
6 7 1
8 7 6
4 8 1
6 5 3
4 6 5
72 78 50
70 89 32
98 135 59
*/
