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Re: Mathematica results different on different

  • To: mathgroup at smc.vnet.net
  • Subject: [mg125585] Re: Mathematica results different on different
  • From: Nabeel Butt <nabeel.butt at gmail.com>
  • Date: Tue, 20 Mar 2012 02:19:50 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <jk43qf$dtt$1@smc.vnet.net>

Hi David
    Thanks for all your efforts :)
   Number of simulation was set to a large value so the final output should
have a fairly less noise.Infact , my laptop with version 8.0.1 is giving
results correctly.
 I did a step by step comparison of the output of two different versions of
Mathematica(8.0.1 and 8.0.4)  as suggested by Ralph .It seems that the only
thing that differs is the output from SmoothKernelDistribution[] ---in
version 8.0.4 the output is faulty.Parellization wasnt applied at this
point and so why did 8.0.4 result in faulty mechanism inside
SmoothKernelDist..[] function. Almost all hardware using 8.0.4 are giving
faulty outputs---I theoretically verified that SmoothKernelDist..[] with
default 'options' in 8.0.4 gives faulty output whereas in 8.0.1 it gives
the correct output.
    Your email much appreciated ! Have a great day !
         Nabeel
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Nabeel Butt
UWO,London
Ontario, Canada



On Mon, Mar 19, 2012 at 6:00 AM, David Bailey <dave at removedbailey.co.uk>wrote:

> On 18/03/2012 07:45, Nabeel Butt wrote:
> > Hi Guys ...
> >       I run a piece of code on two different computers (different
> hardwares)
> > and I get different results.I think its something to do with overflow or
> > different precision on systems ? Personally I think my laptop with an
> > inferior hardware is giving me correct results. The code does involve
> some
> > simulation but running the simulation gives the same result on one
> > particular computer but different for different computers ! You can run
> and
> > tell me what answers you are getting ....Thanks in advance....and my code
> > is below ........
>
> When I run this on 8.0.4 on Windows 64-bit XP, I get a graph with 4
> points, in roughly a straight line. The last point is at (approx)
> {0.25,0.0040}, the first at approx {0.161,0.00245} .
>
> Possible reasons for varying answers:
>
> 1)     Random numbers not initialised to the same point.
>
> 2)     Possible slight hardware differences between 32 and 64-bit PC's
>
> Parallel constructions could give problems if used incorrectly. This
> might vary depending on the number of cores available.
>
> David Bailey
> http://www.dbaileyconsultancy.co.uk
>
>
>



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