Very Computer

by **Jonathan I. Kame** » Tue, 19 Mar 1991 14:40:12

|> I could use some help in generating random numbers. The problem I am having
|> is that I get the same set of numbers each time that I run the program. I
|> have tried using srandom (seed) and entering the seed from the keyboard,
|> but this also returns the same random number. Any help would be greatly
|> appreciated!

I have no problem at all using srandom() and random() to get random numbers,
and I expect most of the other readers of this newsgroup have no problem
either, so it's really impossible for us to diagnose the problem you are
having unless you tell us more specifically exactly what your code is doing.
For example, it would help if you would provide a short test program that
doesn't work (i.e. gets the same random numbers each time) for you.

--
Jonathan Kamens USnail:
MIT Project Athena 11 Ashford Terrace

Office: 617-253-8085 Home: 617-782-0710

by **Miles ONe** » Tue, 19 Mar 1991 14:06:43

Quote:Michael A. Sapienza writes:

!I could use some help in generating random numbers. The problem I am having
!is that I get the same set of numbers each time that I run the program. I
!have tried using srandom (seed) and entering the seed from the keyboard,
!but this also returns the same random number. Any help would be greatly
!appreciated!

On what? Using what?

Sounds like your srand() (srandom?) is broken. But the easy way
(if srand() works) is to say

srand ((int) time (0));

(assuming you are on a UNIX system).

You might also check out the drand48() man page.

-Miles

Miles O'Neal

by **Peter La** » Tue, 19 Mar 1991 20:42:28

>|> I could use some help in generating random numbers. The problem I am having
>|> is that I get the same set of numbers each time that I run the program. I
>|> have tried using srandom (seed) and entering the seed from the keyboard,
>|> but this also returns the same random number. Any help would be greatly
>|> appreciated!
> I have no problem at all using srandom() and random() to get random numbers,
>and I expect most of the other readers of this newsgroup have no problem
>either, so it's really impossible for us to diagnose the problem you are
>having unless you tell us more specifically exactly what your code is doing.
>For example, it would help if you would provide a short test program that
>doesn't work (i.e. gets the same random numbers each time) for you.

There was a bug in (s?)random() in Ultrix 2.0 and 2.2, where srandom
calls with the same seed did not generate repeatable sequences.
This seems to be fixed in Ultrix 4.0, at least the RISC version.
The response from DEC at the time was that it should be fixed in 3.0.

For Michael, you should specify at least the OS version and hardware
you are having problems with for queries like this. A small code example
as Jonathan suggests also makes it easier for people to help you.

--
Peter Lamb

Integrated Systems Laboratory
ETH-Zentrum, 8092 Zurich

by **Sanyee Ta** » Tue, 19 Mar 1991 12:16:39

Obviously your seed doesn't work, the randow number generator simply takes a
default seed. What machine and what kind function call you use?

by **Metallica Rul** » Mon, 01 Apr 1991 06:32:26

>|> I could use some help in generating random numbers. The problem I am having
>|> is that I get the same set of numbers each time that I run the program. I
>|> have tried using srandom (seed) and entering the seed from the keyboard,
>|> but this also returns the same random number. Any help would be greatly
>|> appreciated!

I have encountered the problem before, and my soulution to it has been to
seed the generator with a diriviative of the seconds in the clock/time.
Because each of the seconds in the time keep increasing from I think 1 Jan 1970.
So each seed will be different then the others, and you will always or should
get a different rand each time you run it.

Hope this helps...
Chuck
--

Very Computer

Trying to generate random random numbers!

Trying to generate random random numbers!

Trying to generate random random numbers!

Trying to generate random random numbers!

Trying to generate random random numbers!

Trying to generate random random numbers!