I have an array which stores values of precalculate results at certain
positions (x,y):

Theoretical, it would look like this:

Dim sngArr(200000,200000) as single
For example sng(1,1) would be 0.003923

Of course this is not possible due to the memory capacity.
Any wild ideas how you would do that?
Any input is welcome!

Put the points in an array, then loop through it. Example air code:

Private Type TMyPoints
    x As Long
    y As Long
    Value As Single
End Type

Private MyPoints() As TMyPoints
Private MyPointsCount As Long

Private Sub Form_Load()
    ReDim MyPoints(1 To 10000)  ' Initial size
End Sub

Private Sub AddPoint(x As Long, y As Long, Value As Single)

    If MyPointsCount >= UBound(MyPoints) Then
        ' Time to enlarge the array
        ReDim Preserve MyPoints(1 To UBound(MyPoints) + 10000)
    End If

    MyPointsCount = MyPointsCount + 1
    MyPoints(MyPointsCount).x = x
    MyPoints(MyPointsCount).y = y
    MyPoints(MyPointsCount).Value = Value
End Sub

Private Function GetPoint(x As Long, y As Long, ByRef bNotFound As Boolean)
As Single
    Dim i As Long

    For i = 1 To MyPointsCount
        If x = MyPoints(i).x And y = MyPoints(i).y Then
            GetPoint = MyPoints(i).Value
            Exit Function
        End If
    Next
    If i = MyPointsCount + 1 Then
        ' Point not found
        bNotFound = True
    End If
End Sub

Another approach is to use a collection, and use x*y as a key. This is
probably faster if you have large number of items, but uses more memory.

Show quote Hide quote I think you migth have missed this line in the OP's post ;-)

    Dim sngArr(200000,200000) as single

He's going to need to have data of that size on disk.

Mike

On 10/09/2010 08:17, Mike Williams wrote:
Show quoteHide quoteI think people are more likely to have 149GB of disk space than memory :p

Exactly, which is why I said he needs to have it on disk. Mind you, having
said that, I can remember the time when I would have said you're not gonna'
fit data of that huge size (8KB) in memory! Who knows what the future will
bring ;-)

Mike

On 10/09/2010 09:47, Mike Williams wrote:
You want one of these then :)
http://www.oracle.com/us/products/servers-storage/servers/x86/sun-fire-x4800-server-077287.html

On Sep 10, 5:32 pm, Anders Jorgenson <a.j***@lycos.com> wrote:
http://www.vb-helper.com/tut2.htm

"This article describes triangular arrays, sparse arrays, and other
powerful data structures that can save you memory in your Visual Basic
and VBA applications. "

"At certain positions" would tend to indicate not all positions
need to be represented.  If you only need a few thousand
points to be represented, then use the sparse array.
(linked lists)

If you need several million points to be present,
then look at managing the data in disk files....

LFS

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