* greater than or equal to that.
   */
  private static int partition(double[] array, int from, int to) {
    // Select a pivot, and move it to the start of the slice i.e. to index from.
    movePivotToStartOfSlice(array, from, to);
    double pivot = array[from];

    // Move all elements with indexes in (from, to] which are greater than the pivot to the end of
    // the array. Keep track of where those elements begin.