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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