cross-product.kt

// matrix cross-product
infix fun x(other: Matrix): Matrix {
  require(cols == other.rows)
  val res = Matrix(rows, other.cols, Array(rows * other.cols) { 0.0 })
  for (i in 0 until rows) {
    for (j in 0 until other.cols) {
      for (k in 0 until cols) res[i,j] += (this[i,k] * other[k,j])
    }
  }
  return res
}