Re: [Flashcoders] Whats the deal with AS3 Math.random?
Math.random generates psuedo-random numbers. If you want to have
something that looks more random, try calling Math.random a random
number of times before using the numbers.
Use a true random number to determine the number of times to call it in
the initial run.
Suggestion: the modulus 100 of the number of milli-seconds since
midnight (or some arbitrary date/time).
This should give you at least 100 different pseudo-ransom strings.
increase the modulus to get more.
I believe that you can get hardware devices that will give you truly
random numbers, if that is really required.
As John von Neumann said in 1961 "Anyone who considers arithmetical
methods of producing random digits is of course, in a state of sin."
We are all forced to chose between lesser and greater sins by our need
for economical solutions.
Ron
Sascha wrote:
Hi,
Why is it when I use Math.random to generate 10 random integers I get the
same pattern of numbers almost every time. Starting the SWF movie ten times
and I have 6-8 times the same pattern of numbers. What's going on there?
Almost looks as if the compiler sets pre-compiled numbers.
Using this ...
var str:String = "";
for (var i:int = 0; i < 10; i++)
{
str += Math.floor(Math.random() * 100) + ",
";
}
trace(str);
... and running the SWF movie ten times, I get this ...
88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
43, 69, 70, 96, 39, 97, 8, 74, 29, 65,
50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
This is the first time I experience this. Is there any solution to fix
this?
Thanks,
Sascha
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RE: [Flashcoders] Whats the deal with AS3 Math.random?
> Hi, > > Why is it when I use Math.random to generate 10 random > integers I get the same pattern of numbers almost every time. > Starting the SWF movie ten times and I have 6-8 times the > same pattern of numbers. What's going on there? Most randomisation algorithms are based on a 'seed' value which is passed through a complicated function to produce a new result. This allows programmes containing random numbers to be tested. I don't know about AS3, but certainly up to now there's been no way to specify the random seed, and by the look of your test, it's reset when Flash restarts (you might want to compare the browser with the standalone player, though). You can specify the randomseed for the BitmapData.noise and perlinNoise functions, so you could use these to create more variable data. Danny ___ Flashcoders@chattyfig.figleaf.com To change your subscription options or search the archive: http://chattyfig.figleaf.com/mailman/listinfo/flashcoders Brought to you by Fig Leaf Software Premier Authorized Adobe Consulting and Training http://www.figleaf.com http://training.figleaf.com
RE: [Flashcoders] Whats the deal with AS3 Math.random?
I've noticed that my random functions aren't nearly as random as I would
like (I see annoying patterns all the time) - it seems the same set of
numbers pop up frequently for each session. Good idea Ron.
Jason Merrill
Bank of America
Learning & Organizational Effectiveness
>>-Original Message-
>>From: [EMAIL PROTECTED] [mailto:flashcoders-
>>[EMAIL PROTECTED] On Behalf Of Ron Wheeler
>>Sent: Monday, November 27, 2006 9:45 AM
>>To: Flashcoders mailing list
>>Subject: Re: [Flashcoders] Whats the deal with AS3 Math.random?
>>
>>Math.random generates psuedo-random numbers. If you want to have
>>something that looks more random, try calling Math.random a random
>>number of times before using the numbers.
>>Use a true random number to determine the number of times to call it
in
>>the initial run.
>>Suggestion: the modulus 100 of the number of milli-seconds since
>>midnight (or some arbitrary date/time).
>>This should give you at least 100 different pseudo-ransom strings.
>>increase the modulus to get more.
>>
>>I believe that you can get hardware devices that will give you truly
>>random numbers, if that is really required.
>>
>>As John von Neumann said in 1961 "Anyone who considers arithmetical
>>methods of producing random digits is of course, in a state of sin."
>>
>>We are all forced to chose between lesser and greater sins by our need
>>for economical solutions.
>>
>>Ron
>>
>>Sascha wrote:
>>> Hi,
>>>
>>> Why is it when I use Math.random to generate 10 random integers I
get the
>>> same pattern of numbers almost every time. Starting the SWF movie
ten times
>>> and I have 6-8 times the same pattern of numbers. What's going on
there?
>>> Almost looks as if the compiler sets pre-compiled numbers.
>>>
>>> Using this ...
>>>
>>> var str:String = "";
>>>
>>> for (var i:int = 0; i < 10; i++)
>>> {
>>> str += Math.floor(Math.random() * 100) +
",
>>> ";
>>> }
>>> trace(str);
>>>
>>> ... and running the SWF movie ten times, I get this ...
>>>
>>> 88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
>>> 43, 69, 70, 96, 39, 97, 8, 74, 29, 65,
>>> 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
>>> 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
>>> 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
>>> 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
>>> 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
>>> 88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
>>> 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
>>> 88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
>>>
>>> This is the first time I experience this. Is there any solution to
fix
>>> this?
>>>
>>> Thanks,
>>> Sascha
>>>
>>>
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>>> To change your subscription options or search the archive:
>>> http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
>>>
>>> Brought to you by Fig Leaf Software
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>>>
>>>
>>>
>>___
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RE: [Flashcoders] Whats the deal with AS3 Math.random?
Thanks Ron and Danny!
I knew that the random numbers are not truly random and that the seed cannot
be changed but the random number patterns I get now are pretty hefty, I
think this wasn't like that in AS2 times.
I will try to fumble with the date object to get a better seed.
Sascha
> -Original Message-
> From: [EMAIL PROTECTED] [mailto:flashcoders-
> [EMAIL PROTECTED] On Behalf Of Ron Wheeler
> Sent: Monday, 27 November, 2006 23:45
> To: Flashcoders mailing list
> Subject: Re: [Flashcoders] Whats the deal with AS3 Math.random?
>
> Math.random generates psuedo-random numbers. If you want to have
> something that looks more random, try calling Math.random a random
> number of times before using the numbers.
> Use a true random number to determine the number of times to call it in
> the initial run.
> Suggestion: the modulus 100 of the number of milli-seconds since
> midnight (or some arbitrary date/time).
> This should give you at least 100 different pseudo-ransom strings.
> increase the modulus to get more.
>
> I believe that you can get hardware devices that will give you truly
> random numbers, if that is really required.
>
> As John von Neumann said in 1961 "Anyone who considers arithmetical
> methods of producing random digits is of course, in a state of sin."
>
> We are all forced to chose between lesser and greater sins by our need
> for economical solutions.
>
> Ron
>
> Sascha wrote:
> > Hi,
> >
> > Why is it when I use Math.random to generate 10 random integers I get
the
> > same pattern of numbers almost every time. Starting the SWF movie ten
times
> > and I have 6-8 times the same pattern of numbers. What's going on there?
> > Almost looks as if the compiler sets pre-compiled numbers.
> >
> > Using this ...
> >
> > var str:String = "";
> >
> > for (var i:int = 0; i < 10; i++)
> > {
> > str += Math.floor(Math.random() * 100) + ",
> > ";
> > }
> > trace(str);
> >
> > ... and running the SWF movie ten times, I get this ...
> >
> > 88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
> > 43, 69, 70, 96, 39, 97, 8, 74, 29, 65,
> > 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
> > 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
> > 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
> > 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
> > 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
> > 88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
> > 50, 32, 82, 45, 39, 74, 96, 5, 7, 9,
> > 88, 87, 35, 69, 73, 11, 93, 40, 39, 19,
> >
> > This is the first time I experience this. Is there any solution to fix
> > this?
> >
> > Thanks,
> > Sascha
> >
> >
> > ___
> > Flashcoders@chattyfig.figleaf.com
> > To change your subscription options or search the archive:
> > http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
> >
> > Brought to you by Fig Leaf Software
> > Premier Authorized Adobe Consulting and Training
> > http://www.figleaf.com
> > http://training.figleaf.com
> >
> >
> >
> ___
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> http://chattyfig.figleaf.com/mailman/listinfo/flashcoders
>
> Brought to you by Fig Leaf Software
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Re: [Flashcoders] Whats the deal with AS3 Math.random?
And yet another random number generator library (was posted at were-
here.com a long long time ago). All open source, credit for use is
nice though. :)
This one is a linear congruential generator. I've never tested the
output against anything, so at best, this may or may not work
properly for your needs.
cheers,
jon
Jon Bradley
VFX Artist / Animator
Post Central, Inc.
[EMAIL PROTECTED]
www.cherrycrushthemovie.com
/** BEGIN LCG.as */
/**
* Class com.jbradley.math.LCG
* AuthorJon Bradley
* Version 1.0
* Description Implementation of 48-bit Linear Congruential Pseudo-
Random Number Generator
*
---
* Last update: November 3, 2005 - Converted to AS 2.0
*
---
* 48-bit Linear Congruential Algorithm
* Produces pseudo-random number which can be seeded manually or by a
default time variable.
*
* Source: Computational Nuclear Physics Group, United States Government
* RNG - Random Number Generator algorithms
*
* This implementation is limited to the 48-bit version, which is
still computationally
* inaccurate in Flash due to a 32-bit limitation. It is also not
statistically a sound
* random number generator due to patterns in the low order sequences
and is not a
* cryptographically secure algorithm. It can be made secure by using
a cryptographic hash
* function to generate an initial random number state from a pair of
integers (keys).
*
* The algorithm implementation is as described in the RNG library
published by the
* Lawrence Livermore National Laboratory - http://nuclear.llnl.gov/
CNP/rng/rngman/
*
* Converted to Actionscript by Jon Bradley, 2003
*
---
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
are met:
*
* - Redistributions of source code must retain the above
copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above
copyright
* notice, this list of conditions and the following disclaimer
in the
* documentation and/or other materials provided with the
distribution.
*
* - Neither the name of this software nor the names of its
contributors
* may be used to endorse or promote products derived from this
software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
---
*
* Usage:
*
*Default:
*rGen = new LCG();
*
*Specific seed - may use new Date.getTime() ):
*rGen = new LCG( 1 );
*
* Methods:
*
*init(t:Number)
*Initializes LCG with a time seed. If t is not supplied or
*is NaN, default is used.
*
*getSeed():Number
*Returns initial time seed used to start the system. Recall
that the actual seed
*used in the algorithm is time&M, where M is 2.8^14. The
returned number maybe
*be passed back in to init to restart the random sequence:
*
*rGen.init( rgen.getSeed() )// Will restart system
with original seed
*rGen.init()// Will restart system
with new seed
*
*random()
*Shortcut method to randomReal48()
*
*randomReal48()
*Returns a random 48-bit floating point number on interval
[0,1).
*Note that this currently will not work properly in Flash due
to the limitations
*of the number type. Results are with only 32-bit precision.
(verify this?)
*
**/
class com.jbradley.math.LCG {
/* Period parameters */
static var M = Math.pow(2.8, 14); /* Period of LCG */
static var A = 2862933555777941757; /* 48-bit Mersenne Prime */
static var C = 3037000493; /* 16-bit prime? */
var time:Number = 0;
var seed:Number = 0;
f
