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Re: Problem with Solve and NSolve

  • To: mathgroup at smc.vnet.net
  • Subject: [mg122473] Re: Problem with Solve and NSolve
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Sat, 29 Oct 2011 07:13:01 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

On 10/28/11 at 5:35 AM, gvicente at gmail.com (V. Williams) wrote:

>I've recently tried Mathematica 8.0.1, and I've found that it's
>unable to compute Solve[x^3*Sin[x]==1,x] (and the same with NSolve),
>which gives an error: Solve::nsmet: This system cannot be solved
>with the methods available to Solve

>WolframAlpha solves it without problems, so what's wrong with
>Mathematica?

NSolve and Solve are primarily designed to address polynomial
problems. They will solve *some* non-polynomial problems but far
from all. This particular problem is easily solved by
Mathematica using FindRoot. That is:

In[9]:= FindRoot[x^3*Sin[x] - 1, {x, 1}]

Out[9]= {x->1.04879}

So, I would guess WolframAlpha is using methods similar to what
are used in FindRoot.




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