Function matrixMultiply

Maths/Fibonacci.js:117–136

(A, B)

// both matrices must have same-type numeric values
// either both BigInt or both Number
const matrixMultiply = (A, B) => {
  A = copyMatrix(A)
  B = copyMatrix(B)
  const isBigInt = typeof A[0][0] === 'bigint'
  const l = A.length
  const m = B.length
  const n = B[0].length // Assuming non-empty matrices
  const C = Array(l)
    .fill(null)
    .map(() => Array(n).fill())
  for (let i = 0; i < l; i++) {
    for (let j = 0; j < n; j++) {
      C[i][j] = isBigInt ? 0n : 0
      for (let k = 0; k < m; k++) {
        C[i][j] += A[i][k] * B[k][j]
      }
    }
  }
  return C
}

/**
 * Computes A raised to the power n i.e. pow(A, n) where A is a square matrix