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MathGroup Archive 2005

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Re: Re: can anyone solve this equation?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg58187] Re: [mg58159] Re: can anyone solve this equation?
  • From: Chris Chiasson <chris.chiasson at gmail.com>
  • Date: Tue, 21 Jun 2005 06:03:24 -0400 (EDT)
  • References: <d8rhj9$i7n$1@smc.vnet.net> <200506200952.FAA26966@smc.vnet.net> <acbec1a4050620141519a78e91@mail.gmail.com> <p06230935bedd38f9b92d@130.95.156.21>
  • Reply-to: Chris Chiasson <chris.chiasson at gmail.com>
  • Sender: owner-wri-mathgroup at wolfram.com

Yes, I was just wondering about how you were able to visualize the
equation, breaking it into appropriate constants. I will search the
archives and see if anyone has come up with a general method for
braking things into constants. (something like:
SubstituteConstants[expr,Nonconstants->{a,b,e}], where the result
would be the expression and a list of replacement rules that could be
used to "restore" the original expression)

I (think I) once ran into an equation/problem where the answer was a
product log of a constant, but if that constant was given to
Mathematica as the addition of two other constants, it would return
the expression unsolved.

On 6/20/05, Paul Abbott <paul at physics.uwa.edu.au> wrote:
> >I agree that subscripted expressions look better. However, I run into
> >many instances where Mathematica does not treat subscripted variables
> >as symbols.
> 
> Symbolize in Utilities`Notation` is designed to do exactly that (and
> in some display formats, such as InputForm, it automatically actually
> uses \[UnderBracket] anyway).
> 
> >Notation commands with appropriate pattern matching can
> >take care of converting the unbracketed expressions to more easily
> >readable ones, but I didn't want to complicate the situation any more
> >than it already was.
> 
> Indeed -- to even read and digest your expression I used
> pattern-matching several times to reduce the expression to something
> more manageable.
> 
> Cheers,
> Paul
> 
> >Sincere thanks to both Paul and Pratik for the solutions; I will be
> >testing them shortly.
> >
> >On 6/20/05, Paul Abbott <paul at physics.uwa.edu.au> wrote:
> >>  In article <d8rhj9$i7n$1 at smc.vnet.net>,
> >>   Chris Chiasson <chris.chiasson at gmail.com> wrote:
> >>
> >>  > Can anyone solve the following equation (for theta_4)?
> >>
> >>  Essentially, you are solving the equation
> >>
> >>    FullSimplify[Solve[a - Cos[t] - Sqrt[R^2 - Sin[t]^2] == x, t]]
> >>
> >>  where x = 2 n rhs/d is a constant multiple of your right-hand side, rhs,
> >>  t is theta_4, and a = R + 2/(c - 1) + 1. This is, of course, trivial. I
> >>  expect that Solve struggles with your expression because of the length
> >>  and/or complexity of rhs.
> >>
> >>  To me, using \[UnderBracket] makes your input expression unreadable.
> >>  Only an engineer would work with such expressions!
> >>
> >>  Personally, I like using subscripted expressions in Mathematica. They
> >>  are not without their difficulties and subtleties -- but are preferable
> >>  to using \[UnderBracket].
> >>
> >>  Cheers,
> >>  Paul
> >>
> >>  --
> >>  Paul Abbott                                      Phone: +61 8 6488 2734
> >>  School of Physics, M013                            Fax: +61 8 6488 1014
> >>  The University of Western Australia         (CRICOS Provider No 00126G)
> >>  AUSTRALIA                               http://physics.uwa.edu.au/~paul
> >>          http://InternationalMathematicaSymposium.org/IMS2005/
> >>
> >>
> >
> >
> >--
> >Chris Chiasson
> >http://chrischiasson.com/
> >1 (810) 265-3161
> 
> 
> 


-- 
Chris Chiasson
http://chrischiasson.com/
1 (810) 265-3161


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