Unique Random Number Sequences??

Anyone now how to, within a self contained function, generate a sequence of UNIQUE random numbers all in a given range?

Based, perhaps, around a call somthing like.....


'************************************************************************
' Paramaters
' NumOfNumbers: Number of unique random numbers to generate
' minRange: Minimum value of any returned random number
' maxRange: Maximum value of any returned random number
' Returns
' randomSequence(): Array of UNIQUE random numbers
'************************************************************************
Public Function getRandomSequence(NumOfNumbers As Integer, minRange As Long, maxRange As Long) As randomSequence()

End Function

1. You can only generate pseudo random numbers
2. What do you mean unique? Must the sequence be unique? Or the numbers in the sequence?

The numbers in the sequence need to be unique

There are two algorithms that I can think of:
- max-min>>numberOfNumbers (much smaller):
    - generate a list, and test each number against the previous numbers in the list, if it is not unique, try again
- else:
    - generate a list of all numbers in the range min...max, randomly shuffle that sequence, and only keep the top n numbers.

The suggested syntax using a Function does not seem valid, although a close approximation could be made with a User Type variable containing an array. The following is a possible alternative.

Code:

---

Dim RandomValue() As Long
. . .
Public Sub RandomArrayFiller(NumOfNumbers As Integer, minRange As Long, _
                                    maxRange As Long)
Redim RandomValue(0 to NumOfNumbers) As Long ‘Value zero for luck.
Dim TentativeValue As Long
Dim J As Integer
Dim LastRandy As Integer

Randomize  ‘this could be part of Main Line initialize code.
LastRandy = 0
J = 1
TentativeValue = CLng( minRange + (maxRange - minRange)*Rnd)

Do
      Select Case True
              Case J > LastRandy
                    RandomValue(J) = TentativeValue
                    TentativeValue = CLng(minRange _
                                              + (maxRange - minRange)*Rnd)
                    J = 1
                    LastRandy = LastRandy + 1
              Case TentativeValue = RandomValue(J)
                    TentativeValue = CLng( minRange _
                                          + (maxRange - minRange)*Rnd)
                    J = 1
              Case Else
                    J = J + 1
          End Select

  Loop While LastRandy < NumberOfNumbers

End Sub

---

Caveat emptor: I neither compiled nor tested the above.

BTW: If you are simulating some random process, it might not be correct to eliminate duplicates.