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Re: How to parse equations

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  • Subject: [mg91640] Re: How to parse equations
  • From: Bill Rowe <readnews at>
  • Date: Sat, 30 Aug 2008 01:52:27 -0400 (EDT)

On 8/29/08 at 4:25 AM, Stuart.Nettleton at (Stuart Nettleton)

>Hi, I am a bit stuck on how to convert the following set of
>equations to a list of variables:

>eqns = {
>x[1] + y[1] + z[1],
>x[1] + 3 z[1] + u[1]^2,
>z[1] - u[1] - 16,
>u[1] - 5};

>to give.. {{ x[1], y[1], z[1]},{x[1], z[1], u[1]},{z[1],
>u[1],}, {u[1]}}

>Any thoughts would be appreciated! Thanks, Stuart

You have not specified any equation in your post. You have set
the variable eqns to a list of expressions. Nor is it clear what
it is you are attempting to achieve.

You say you want a list of *variables* but do not specify any
relationships between the variables you want and the expressions
you start with. In your example, the part following "to give..."
shows things of the form x[1] which is the function evaluated at
1, not a variable.

If you provide more clarity as to what you are attempting to do
I am sure you will get useful feedback here.

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