[Mono-osx] bug in Random
Duane Wandless
duane at wandless.net
Sun Jan 25 15:46:30 EST 2009
It is a commercial app. And in the wild already on Windows.
Reimplementing the random generator seems trivial but because of that it is
not, though not impossible. The interaction between client and server
relies on the same numbers being generated given the seed. It is not a
highly secure algorithm. It is pseudo after all.
There are many tasks more important to Mono than the Random class... I do
understand. But it never hurts to ask ... especially since the Mono team is
willing to respond and offer assistance, which I greatly appreciate.
We will find a solution to this problem and in the future not rely on the MS
Random class.
And I'm still looking for more official support on the iPhone!
Thanks again!
Duane
On Sun, Jan 25, 2009 at 3:26 PM, Geoff Norton <gnorton at novell.com> wrote:
> Duane,
>
> Is there some reason juts copying our Random class into your library
> doesn't work for you? Its MIT/X11 licensed so you have no concerns if
> your project is commercial, and you'll get the same results on all CLRs
> then.
>
> -g
>
> On Sun, 2009-01-25 at 15:17 -0500, Duane Wandless wrote:
> > Rodrigo is on the Mono team and has already answered you.
> >
> > Not very obvious he (kumpera at gmail.com) is on the Mono team...
> > actually it just seemed like the response was from a random mono
> > user. Ha! Joke aside, that is what I thought.
> >
> >
> > Anyway... for what it is worth, I disagree. The advantage of having
> > the same pseudo random numbers given the same seed is important. Yes
> > I can write my own algorithm to accomplish that but I prefer not to
> > reinvent the wheel. That was and most of the time is one of the
> > biggest advantages of Mono. I do not have to rewrite code... I can
> > reuse from Windows to Mac to Linux and I can focus on the core
> > functionality of my applications. Not random differences between the
> > OSes or random programming languages specific to that OS.
> >
> >
> > My only request is that the decision not to provide the same
> > functionality as the Microsoft's library in this case was indeed by
> > design and not a random decision by some random developer.
> >
> >
> > Okay -- enough random jokes... but the request is legit.
> >
> >
> > Thanks for the responses.
> > Duane
> >
> >
> > On Sun, Jan 25, 2009 at 2:30 PM, Geoff Norton <gnorton at novell.com>
> > wrote:
> > Rodrigo is on the Mono team and has already answered you.
> >
> >
> > On Sun, 2009-01-25 at 14:24 -0500, Duane Wandless wrote:
> > > Hello Mono-team... Can you please provide an answer? Was
> > the
> > > intention to use a different algorithm for the Random class,
> > or was
> > > that a mistake? Honestly I cannot see a technical reason to
> > use a
> > > different one.
> > >
> > >
> > > Thanks.
> > >
> > > On Mon, Jan 19, 2009 at 5:43 PM, Rodrigo Kumpera
> > <kumpera at gmail.com>
> > > wrote:
> > > Your application depends on an implementation detail
> > of the MS
> > > runtime.
> > > There is no guarantee either that they won't change
> > the Random
> > > algorithm.
> > >
> > > This is unfortunate to your application but the
> > solution is
> > > pretty simple, copy mono's
> > > implementation to your project and rely on it
> > instead of an
> > > external prng.
> > >
> > >
> > >
> > >
> > > On Mon, Jan 19, 2009 at 8:38 PM, MacUser
> > > <atlas at spiralgraphics.biz> wrote:
> > >
> > > This is also a point of concern for me. My
> > code ,
> > > written on Microsoft .NET,
> > > relied on the fact that using the same seed
> > will
> > > always produce the same
> > > series of numbers. To port to Mono, not
> > only would I
> > > need Mono's Random()
> > > to be consistant across all Mono platforms,
> > but also
> > > consistant to the
> > > results that Microsoft's Random() produces.
> > >
> > > By the way, I work in the algorithmic
> > graphics
> > > generation area, where an
> > > image produced with the same input values
> > must always
> > > look the same
> > > regardless of the platform the app is
> > running on.
> > > This is why reliable
> > > seeding is so important.
> > >
> > >
> > >
> > >
> > > Rodrigo Kumpera wrote:
> > > >
> > > > It doesn't state the the algorithm has to
> > be the
> > > same, just that it must
> > > > be
> > > > reproducible given the same seed.
> > > >
> > > > On Mon, Jan 19, 2009 at 3:27 PM, Duane
> > Wandless
> > > <duane at wandless.net>
> > > > wrote:
> > > >
> > > >> That is a valid question. From MSDN, the
> > Random
> > > class is a Pseudo-random
> > > >> number generator:
> > > >> The random number generation starts from
> > a seed
> > > value. If the same seed
> > > >> is
> > > >> used repeatedly, the same series of
> > numbers is
> > > generated.
> > > >>
> > > >>
> > >
> > http://msdn.microsoft.com/en-us/library/system.random.aspx
> > > >>
> > > >> The value in this is that given a seed
> > will produce
> > > the same sequence of
> > > >> random numbers. So if the client and
> > server both
> > > know the seed then
> > > >> the algorithm will work correctly on both
> > > platforms.
> > > >>
> > > >>
> > > >> On Mon, Jan 19, 2009 at 12:09 PM, Matt
> > Emson
> > > >> <memsom at interalpha.co.uk>wrote:
> > > >>
> > > >>> Duane Wandless wrote:
> > > >>>
> > > >>>> Maybe I incorrectly assume that the
> > pseudo-random
> > > number should be the
> > > >>>> same on both platforms... but I believe
> > that it
> > > should be a predictable
> > > >>>> sequence given the same seed.
> > > >>>>
> > > >>> Maybe this is a silly question, but why
> > would you
> > > want your *random*
> > > >>> number to be the same on both platforms,
> > more so
> > > "a predictable
> > > >>> sequence"?
> > > >>> Sure I'm missing something obvious,
> > but... ?!
> > > >>>
> > > >>
> > > >>
> > > >>
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> > > >>
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> > > >>
> > > >>
> > > >
> > > >
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> > >
> > >
> > > --
> > > View this message in context:
> > >
> > http://www.nabble.com/bug-in-Random-tp21544091p21553211.html
> > > Sent from the Mono - OSX mailing list
> > archive at
> > > Nabble.com.
> > >
> > >
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