matrix.kt

data class Matrix(val rows: Int, val cols: Int) {
  
  lateinit var elements: DoubleArray
  
  private fun index(r: Int, c: Int) = r * cols + c
  
  operator fun get(r: Int, c: Int) = elements[index(r,c)]
  
  operator fun set(r: Int, c: Int, element: Double) {
    elements[index(r,c)] = element
  }
  
  constructor(rows: Int, cols: Int, elements: DoubleArray) : this(rows, cols) {
    this.elements = elements;
  }
}