JavaScript: Matrix Multiplication

To multiply two matrices, A and B, is to calculate the resulting matrix C, where each element C(ij) is equal to the sum of the products of the elements in the corresponding row of the first matrix A(ik), and that of the column of the second matrix B(kj).

Matrix multiplication requires the number of columns in the first matrix to coincide with the number of rows in the second matrix. So the first matrix must necessarily be compatible with the second matrix. Multiplication of a matrix of size M×N by a matrix of size N×K results in a matrix of size M×K.

matrix.js

Write and export as default a function that takes two matrices and returns the result of their multiplication.

Examples

import multiply from './matrix.js';

const matrixA = [[1, 2], [3, 2]];
const matrixB = [[3, 2], [1, 1]];

multiply(matrixA, matrixB);
// [[5, 4], [11, 8]]

const matrixC = [
  [2, 5],
  [6, 7],
  [1, 8],
];
const matrixD = [
  [1, 2, 1],
  [0, 1, 0],
];

multiply(matrixC, matrixD);
// [
//   [2, 9, 2],
//   [6, 19, 6],
//   [1, 10, 1],
// ]

Tips

• Matrix multiplication algorithm
• Visual demonstration of a matrix multiplication