Re: Re: Re: Weird result in Mathematica 6
- To: mathgroup at smc.vnet.net
- Subject: [mg76626] Re: [mg76574] Re: [mg76431] Re: [mg76393] Weird result in Mathematica 6
- From: János <janos.lobb at yale.edu>
- Date: Fri, 25 May 2007 06:21:32 -0400 (EDT)
- References: <26727995.1179743868970.JavaMail.root@m35> <200705220647.CAA19795@smc.vnet.net> <9745176.1179921476358.JavaMail.root@m35> <op.tssgfzliqu6oor@monster.ma.dl.cox.net> <4431163.1179955154502.JavaMail.root@m35> <op.tsstz4blqu6oor@monster.ma.dl.cox.net> <23418457.1179976106322.JavaMail.root@m35> <200705241003.GAA21171@smc.vnet.net>
There are function calls in some OS libraries that are not working correctly on AMD architecture. A good friend of mine in Hungary worked for a software firm and the firm had just AMD machines. The only Intel machine was his laptop. When it came to close out a major upgrade of the firm software, all AMD machines reported problems and only his Intel laptop gave the desired result. All AMDs were changed overnight for Intel machines. J=E1nos On May 24, 2007, at 6:03 AM, DrMajorBob wrote: > I'm using an AMD 3200+ processor, in case that matters. > > Bobby > > On Wed, 23 May 2007 16:37:54 -0500, Andrzej Kozlowski > <akoz at mimuw.edu.pl> > wrote: > >> *This message was transferred with a trial version of CommuniGate(tm) >> Pro* >> That means definitely "platform dependence". It would be >> interesting if >> somone checked this on an Intel Mac. I think it is much more >> likely to >> be the processor than the operating system that makes the difference >> here. I don't know much about such things, but some processor >> specific >> libraries could be responsible for this. >> >> Andrzej >> >> >> On 24 May 2007, at 06:29, DrMajorBob wrote: >> >>> $Version >>> >>> "6.0 for Microsoft Windows (32-bit) (April 20, 2007)" >>> >>> Bobby >>> >>> On Wed, 23 May 2007 16:17:31 -0500, Andrzej Kozlowski >>> <akoz at mimuw.edu.pl> wrote: >>> >>>> *This message was transferred with a trial version of CommuniGate >>>> (tm) >>>> Pro* >>>> Yes, its curious. It might just be "platform dependence" but is >>>> more >>>> likely to be "time of release dependence". Mine is: >>>> >>>> >>>> $Version >>>> >>>> "6.0 for Mac OS X PowerPC (32-bit) (April 20, 2007)" >>>> >>>> Andrzej >>>> >>>> >>>> On 24 May 2007, at 01:37, DrMajorBob wrote: >>>> >>>>> Interesting. But your results are entirely different from mine, >>>>> for >>>>> the same input. >>>>> >>>>>> which explains what is wrong (error messages can tell you a lot, >>>>>> sometimes). >>>>> >>>>> And frequently, they don't. >>>>> >>>>> Here's the error message at THIS machine: >>>>> >>>>> FindRoot::lstol: The line search decreased the step size to >>>>> within \ >>>>> tolerance specified by AccuracyGoal and PrecisionGoal but was >>>>> unable \ >>>>> to find a sufficient decrease in the merit function. You may >>>>> need \ >>>>> more than MachinePrecision digits of working precision to meet >>>>> these \ >>>>> tolerances. >> >>>>> >>>>> Bobby >>>>> >>>>> On Tue, 22 May 2007 06:28:08 -0500, Andrzej Kozlowski >>>>> <akoz at mimuw.edu.pl> wrote: >>>>> >>>>>> *This message was transferred with a trial version of CommuniGate >>>>>> (tm) Pro* >>>>>> I don't see any connection between these two issues. Moreover, >>>>>> I get: >>>>>> >>>>>> FindRoot[h = g, {x, 0}] >>>>>> FindRoot::njnum:The Jacobian is not a matrix of numbers at {x} >>>>>> {0.}. >> >>>>>> {x -> 0.} >>>>>> >>>>>> which explains what is wrong (error messages can tell you a lot, >>>>>> sometimes). Trying a slightly different starting search point: >>>>>> >>>>>> FindRoot[h == g, {x, 0.1}] >>>>>> {x->2.} >>>>>> >>>>>> {g, h} /. % >>>>>> {0., 0.} >>>>>> >>>>>> >>>>>> Andrzej Kozlowski >>>>>> >>>>>> >>>>>> On 22 May 2007, at 15:47, DrMajorBob wrote: >>>>>> >>>>>>> Even worse, FindRoot returns a wrong answer: >>>>>>> >>>>>>> g = Piecewise[{{0, x < 0}, {2 x - x^2, 0 <= x < 4}, {16 x - x^2, >>>>>>> x=B34}}]; >>>>>>> h = x - 2; >>>>>>> FindRoot[h == g, {x, 0}] >>>>>>> {g, h} /. % >>>>>>> >>>>>>> {x->-2.84217*10^-15} >>>>>>> {0, -2.} >>>>>>> >>>>>>> Bobby >>>>>>> >>>>>>> On Mon, 21 May 2007 05:01:21 -0500, Sebastian Meznaric >>>>>>> <meznaric at gmail.com> wrote: >>>>>>> >>>>>>>> I was playing around with Mathematica 6 a bit and ran this >>>>>>>> command >>>>>>>> to >>>>>>>> solve for the inverse of the Moebius transformation >>>>>>>> >>>>>>>> FullSimplify[ >>>>>>>> Reduce[(z - a)/(1 - a\[Conjugate] z) == w && a a\ >>>>>>>> [Conjugate] < 1 >>>>>>>> && >>>>>>>> w w\[Conjugate] < 1, z]] >>>>>>>> >>>>>>>> This is what I got as a result: >>>>>>>> -1 < w < 1 && -1 < a < 1 && z == (a + w)/(1 + w Conjugate[a]) >>>>>>>> >>>>>>>> Why is Mathematica assuming a and w are real? The Moebius >>>>>>>> transformation is invertible in the unit disc regardless of >>>>>>>> whether a >>>>>>>> and w are real or not. Any thoughts? >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> --DrMajorBob at bigfoot.com >>>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> >>>>> --DrMajorBob at bigfoot.com >>>> >>>> >>> >>> >>> >>> --DrMajorBob at bigfoot.com >> >> > > > > -- > DrMajorBob at bigfoot.com ---------------------------------------------- Trying to argue with a politician is like lifting up the head of a corpse. (S. Lem: His Master Voice)
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- Re: Weird result in Mathematica 6
- From: DrMajorBob <drmajorbob@bigfoot.com>
- Re: Re: Weird result in Mathematica 6
- From: DrMajorBob <drmajorbob@bigfoot.com>
- Re: Weird result in Mathematica 6