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http://www.openoffice.org/issues/show_bug.cgi?id=85690
Issue #|85690
Summary|RAND() Rounding off
Component|Spreadsheet
Version|OOo 2.3.1
Platform|PC
URL|
OS/Version|Windows XP
Status|UNCONFIRMED
Status whiteboard|
Keywords|
Resolution|
Issue type|DEFECT
Priority|P3
Subcomponent|code
Assigned to|spreadsheet
Reported by|player001
------- Additional comments from [EMAIL PROTECTED] Tue Jan 29 19:24:34 +0000
2008 -------
It seems that Calc doesn't manage to compare exactly a rand() value to a number
equal or lower than 1E-6. Indeed, the rand() used to compare looks rounded off
in a too high number.
Let's take:
p=1E-7 in Cell B1
enter in A1: IF(RAND()<$B$1;1;0)
Copy-paste until A10000
Set Cell A100001: =Sum of the numbers below
Now let's update the page with F9. You must notice you have about a "1", in the
sum, every 10 tries.
Nevertheless, we should have, in the average : 10000*1E-7=1E-3 which is to say
we should only have one match for 1000 tries.
You'll notice that using p=1E-9 or 1E-10, or whatever lower, gives you, in the
average, such results.
In Basic this loop generates the same results:
For i=1 to 10 000 'or as much as you want
If RND()<1E-7 Then
m=m+1 'i choosed m cause I used that loop to calculte the number
of mutations given by bacterias with a p rate very low
End if
Next i
I checked out that defect with another version (2.3.0 English), on another
computer (still XP). The defect must be due to rounding off errors as I've ever
heard, alas ! that Calc had had difficulties rounding numbers close to the
digits limit (cf. Euler Estimate).
PS: I apologize if it seems confused due to my english, just ask me.
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