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Re: Re: NSolve fails where Solve succeeds!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg43530] Re: [mg43478] Re: NSolve fails where Solve succeeds!
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Fri, 19 Sep 2003 03:41:53 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <bk9jer$t8t$1@smc.vnet.net> <200309180938.FAA10468@smc.vnet.net>
  • Reply-to: murray at math.umass.edu
  • Sender: owner-wri-mathgroup at wolfram.com

Are you objecting to the absence of a (vector) variable on the left-hand 
side of the equation, or just to an equation with a matrix (list of 
equal-length lists) on the left-hand side and a scalar on the right-hand 
side?

If the latter:  Why should Mathematica NOT like {{a,b}, {c,d}} == 0 ? 
After all, it has no trouble returning a reasonable result for:

   ((a, b}, {c, d}} + 0

I'm not talking about the way the language IS, but rather the way it 
OUGHT to be designed!


Jens-Peer Kuska wrote:

> Hi,
> 
> you say that the matrix {{a,b}
>                          {c,d}}
> 
> should be equal to a scalar 0 and you wonder
> why Mathematica dont' like it ...
> 
> I wonder why Solve[] gives a solution at all
> and *this* seems to be the bug. You mean
> 
> NSolve[Flatten[Thread  /@ Thread[{{a, b}, {c, d}} == 0]]]
> 
> you you should tell Mathematica *what* you mean.
> 
> Regards
>   Jens
> 
> 
> Pavel Pokorny wrote:
> 
>>  Dear Mathematica friends
>>
>>   Solve[{{a,b},{c,d}}==0]
>>
>>gives the correct solution in Mathematica 5.0 while
>>
>>   NSolve[{{a,b},{c,d}}==0]
>>
>>fails.
>>
>>Is it a bug or an intention?
>>
>>It would be nice to have Solve and NSolve giving
>>as close results as possible.
>>
>>--
>>Pavel Pokorny
>>Math Dept, Prague Institute of Chemical Technology
>>http://www.vscht.cz/mat/Pavel.Pokorny
> 
> 
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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