How do I add the sum of a series numbers generated by Rnd gen?
 

I need to create the sum of 2,500,000 iterations generated by the Rnd
generator function. I cannot create y=X(1)+X(2)+......X(n) where y is the
sum and x (the first iteration, x(2) the second and so on.

I am assuming you are wanting to do this in a macro as you have used Rnd and
not the worksheet function Rand. You could do it like this

Sub RandomSum()
Dim i As Long
Dim y As Double
For i = 1 To 2500000
y = y + Rnd()
Next i
MsgBox y
End Sub

but it would be a lot more efficient and probably not materially different
to do this:

Sub RandomSum()
Dim i As Integer
Dim y As Double
For i = 1 To 25
y = y + Rnd() * 100000
Next i
MsgBox y
End Sub

Hope this helps
Rowan

"RandomProblems" wrote:

I need to create the sum of 2,500,000 iterations generated by the Rnd
generator function. I cannot create y=X(1)+X(2)+......X(n) where y is the
sum and x (the first iteration, x(2) the second and so on.

Hi,

you need a macor for this. However, you'll always get the same result.
Run my code, in column A you'll see the sum you are looking for (250,
2500... 2.5Mio iterations), in column B you'll see the average, which
will always be the same.

Sub test()
Randomize
x = 0
v = 25
For j = 1 To 5
v = v * 10
For i = 1 To v
x = x + Rnd()
Next
Cells(j, 1).Value = x
Cells(j, 2).Value = x / v
Next j
End Sub

the important part for you is:
for i = 1 to 2500000
x = x+Rnd()
next

arno

"RandomProblems" schrieb im
Newsbeitrag ...
I need to create the sum of 2,500,000 iterations generated by the Rnd
generator function. I cannot create y=X(1)+X(2)+......X(n) where y
is the
sum and x (the first iteration, x(2) the second and so on.

Thanks for the reply. It is exactly what I needed.

"Rowan" wrote:

I am assuming you are wanting to do this in a macro as you have used Rnd and
not the worksheet function Rand. You could do it like this

Sub RandomSum()
Dim i As Long
Dim y As Double
For i = 1 To 2500000
y = y + Rnd()
Next i
MsgBox y
End Sub

but it would be a lot more efficient and probably not materially different
to do this:

Sub RandomSum()
Dim i As Integer
Dim y As Double
For i = 1 To 25
y = y + Rnd() * 100000
Next i
MsgBox y
End Sub

Hope this helps
Rowan

"RandomProblems" wrote:

I need to create the sum of 2,500,000 iterations generated by the Rnd
generator function. I cannot create y=X(1)+X(2)+......X(n) where y is the
sum and x (the first iteration, x(2) the second and so on.

Thank you for the insitefull response. I guess I am going to do some reading.

"arno" wrote:

Hi,

you need a macor for this. However, you'll always get the same result.
Run my code, in column A you'll see the sum you are looking for (250,
2500... 2.5Mio iterations), in column B you'll see the average, which
will always be the same.

Sub test()
Randomize
x = 0
v = 25
For j = 1 To 5
v = v * 10
For i = 1 To v
x = x + Rnd()
Next
Cells(j, 1).Value = x
Cells(j, 2).Value = x / v
Next j
End Sub

the important part for you is:
for i = 1 to 2500000
x = x+Rnd()
next

arno

"RandomProblems" schrieb im
Newsbeitrag ...
I need to create the sum of 2,500,000 iterations generated by the Rnd
generator function. I cannot create y=X(1)+X(2)+......X(n) where y
is the
sum and x (the first iteration, x(2) the second and so on.