RAND() function seeding

[David Gray]

I am a graduate student, and I have an assignment to
"analyze" the random number generator in EXCEL. In KB
article 86523, I found some information about the algorithm
that is used to calculate random numbers using RAND().

Among other things, that article says, "In Microsoft Excel
for Windows, adding randomize=1 to the [Microsoft Excel]
section of the appropriate .INI file for your version of
Microsoft Excel will cause "r" to be determined from the
system clock (which adds a further degree of randomness to
the numbers generated)." Because I am supposed to analyze
the random number generator and write a report about my
findings, I would like to be able to control the seed
value, so my results will be repeatable.

I am running Excel 2002 on Windows 2000 Pro. I can't seem
to find "the appropriate .ini file" on my system. My
system adminstrator says that .ini files don't really exist
any more.

Q: Is there a way in Excel 2002 for a user to control or
initialize the seed value that the RAND() worksheet
function uses?

Some of my research leads me to believe that if I used the
Rnd function in VBA for Excel (where I believe I can
control the seed value -- KB article 129742), that I would
actually be using a different algorithm.

Q: Does anyone know if the Rnd and Randomize functions in
VBA for Excel use the same algorithm as the RAND()
worksheet function?

I would appreciate any help.

Sincerely,

David E. Gray

[Harlan Grove]

"David Gray" wrote...
..

>Among other things, that article says, "In Microsoft Excel
>for Windows, adding randomize=1 to the [Microsoft Excel]
>section of the appropriate .INI file for your version of
>Microsoft Excel will cause "r" to be determined from the
>system clock (which adds a further degree of randomness to
>the numbers generated)." Because I am supposed to analyze
>the random number generator and write a report about my
>findings, I would like to be able to control the seed
>value, so my results will be repeatable.
>
>I am running Excel 2002 on Windows 2000 Pro. I can't seem
>to find "the appropriate .ini file" on my system. My
>system adminstrator says that .ini files don't really exist
>any more.
>
>Q: Is there a way in Excel 2002 for a user to control or
>initialize the seed value that the RAND() worksheet
>function uses?

Note that the cited KB article goes back a ways - it claims to apply to the
original 1.0 Mac version. Anyway, .INI files were used in 16-bit versions of
Windows and 16-bit Windows apps. The Windows Registry is used for similar
information in 32-bit Windows/apps. You may need to add a Randomize value to the
registry key

HKEY_CURRENT_USER\Software\Microsoft\Office\8.0\Excel\Microsoft Excel

set to 0 to see if you can always start with the same seed.

>Some of my research leads me to believe that if I used the
>Rnd function in VBA for Excel (where I believe I can
>control the seed value -- KB article 129742), that I would
>actually be using a different algorithm.
>
>Q: Does anyone know if the Rnd and Randomize functions in
>VBA for Excel use the same algorithm as the RAND()
>worksheet function?

No. VBA's Rnd/Randomize are separate and distinct from Excel's RAND().

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