Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

Find the sum of 12 DIFFERENT random numbers

Posted on 2007-11-18
10
240 Views
Last Modified: 2010-04-30
Experts,

I need to assign a parameter 'b' as the sum of 12 different randomly generated numbers between 0 and 1. How do i do that - should i use a loop?
I need the code to do this automatically and assign the result to a variable 'b' as a value for use in other calcs.

Thanks everyone

Simon
0
Comment
Question by:simondopickup
  • 3
  • 2
  • 2
  • +3
10 Comments
 
LVL 55

Expert Comment

by:Jaime Olivares
ID: 20309115
Is this a homework?
some initial code to start helping you with?

0
 
LVL 25

Expert Comment

by:imitchie
ID: 20309138
I see you included this in Excel, are you after an Excel formula?
0
 
LVL 7

Expert Comment

by:tcicatelli
ID: 20309175
If you're in excel, place the formula =rand() into cells A1 through A12.  Then place the formula =sum(a1:a12) into cell a13.  This will work, but you will get a different answer everytime the spreadsheet recalculates.
0
Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

 
LVL 25

Accepted Solution

by:
imitchie earned 500 total points
ID: 20309192
if you're after Excel VBA, then here's something to get you started
it contains a template for a loop (to 5) and in each iteration, calls Rnd() once
the cells(2,i) shows you how it generates a different random value each time
instead of b = Rnd(), you can use b = b + Rnd() to add to b each time
Dim b As Double
b = 0
For i = 1 To 5
    b = Rnd()
    Cells(2, i) = b
Next

Open in new window

0
 

Author Comment

by:simondopickup
ID: 20309307
i need to code this in vb. I dont want to write in cells  - i would rather populate an array and sum the elements..

currently by code is this which is so wrong!

b=rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd
0
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 20309467
Just like imitchie said...
Option Explicit
 
Private Sub Form_Load()
    Randomize
End Sub
 
Private Sub Command1_Click()
    Dim b As Double
    Dim value As Double
    Dim i As Integer
    
    For i = 1 To 12
        value = Rnd
        Debug.Print i, value
        b = b + value
    Next i
    Debug.Print "b = " & b
End Sub

Open in new window

0
 
LVL 76

Expert Comment

by:GrahamSkan
ID: 20309494
Try it like this:

Sub Totalrnd()
    Dim r(11) As Double
    Dim i As Integer
    Dim j As Integer
    Dim d As Double
    Dim bFound As Boolean
    Dim b As Double
    Dim strMessage As String
    i = -1
    Randomize
    Do While i < 11
        d = Rnd()
        bFound = False
        For j = 0 To i
            If d = r(i) Then
                bFound = True
                Exit For
            End If
        Next j
        If Not bFound Then
            i = i + 1
            r(i) = d
            strMessage = strMessage & IIf(i > 0, " + ", "") & d
            b = b + d
        End If
    Loop
    strMessage = b & " = " & strMessage
    MsgBox strMessage
End Sub

0
 
LVL 76

Expert Comment

by:GrahamSkan
ID: 20309516
I did check that each contributory element is different as you asked, but I bet, you couldn't produce two identical random numbers in such a sequence in a thousand years.
0
 
LVL 25

Expert Comment

by:imitchie
ID: 20309578
i thought i'd leave something for your imagination but...
' old: b=rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd+rnd
' new: below, equivalent. drop the 4 lines where the 1 line above was
b = 0;
for i = 1 to 12
  b = b + rnd()
next i

Open in new window

0
 

Author Closing Comment

by:simondopickup
ID: 31409832
Thanks!
0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article will guide you to convert a grid from a picture into Excel format using Microsoft OneNote and no other 3rd party application.
This code takes an Excel list of URL’s and adds a header titled “URL List”. It then searches through all URL’s in column “A”, looking for duplicates. When a duplicate is found, it is moved to the top of the list. The duplicate URL’s are then highlig…
This Micro Tutorial will demonstrate how to use a scrolling table in Microsoft Excel using the INDEX function.
This Micro Tutorial will demonstrate how to create pivot charts out of a data set. I also added a drop-down menu which allows to choose from different categories in the data set and the chart will automatically update.

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question