/*=====================( Quick sort )======================*/
QSort: Procedure Expose stem.
Arg fromX, toX

/*--------------------( Standardwerte )--------------------*/
If Datatype( fromX, "NUM" ) = 0 | fromX < 1 Then fromX = 1
If Datatype( toX, "NUM" ) = 0 | toX > stem.0 Then toX = stem.0

If toX > fromX Then Do
  i = fromX
  j = toX
  k = (fromX + toX) % 2
  x = stem.k
  Do Until i > j
    Do While stem.i >> x; i = i + 1; End
    Do While stem.j << x; j = j - 1; End
    If i <= j Then Do
      xchg = stem.i
      stem.i = stem.j
      stem.j = xchg
      i = i + 1
      j = j - 1
    End
  End
  y = QSort( fromX, j )
  y = QSort( i, toX )
End

Return toX - fromX
/*** End QSort ***/