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Re: WolframAlpha[] give results but not parse!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg114516] Re: WolframAlpha[] give results but not parse!
  • From: Maxim <m.r at inbox.ru>
  • Date: Mon, 6 Dec 2010 06:13:38 -0500 (EST)
  • References: <idd7rr$ngc$1@smc.vnet.net>

On Dec 4, 5:15 am, Murray Eisenberg <mur... at math.umass.edu> wrote:
> In Mathematica 8.0, the following gives the expected explicit
> solution, graphs, etc.:
>
>   WolframAlpha["solve dy/dt=2y(1-y)"]
>
> It even tells me the interpretation as "solve y'(t)=2y(1-y)".  Of
> course, just using input
>
>   =solve dy/dt=2y(1-y)
>
> gives the same results.
>
> However, the following (as well as the Ctrl= input form for it) gives
> no Mathematica translation of the input:
>
>   WolframAlpha["solve dy/dt=2y(y-1)","MathematicaParse"]
>
> It is surprising that WolframAlpha "understands" what I asked but
> cannot actually tell me in Mathematica syntax the same thing!
>
> Or am I missing something?
>
> --
>   Murray Eisenberg                       Internet:  mur... at math.umass.edu
>   Mathematics & Statistics Dept.            Voice:  413-545-2859 (W)
>   University of Massachusetts                     413-549-1020 (H)
>   Amherst, MA 01003                          Fax:  413-545-1801

This is a bit of an implementation detail, but (simplifying things
somewhat) the query goes through the W|A parser first and sometimes
the result of the parse is an expression that can be evaluated on its
own on the client side. In that case you get "MathematicaParse". Other
times the result of the parse is an intermediate form which invokes W|
A scanners. The scanners generate the pods and the pods can contain
"Mathematica plaintext output" fields. You can extract those by doing
WolframAlpha["solve dy/dt=2y(1-y)", "MathematicaForms"].

Maxim Rytin
m.r at inbox.ru


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