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Re: Mathematica- Use a previous equation into the

  • To: mathgroup at smc.vnet.net
  • Subject: [mg111487] Re: Mathematica- Use a previous equation into the
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Tue, 3 Aug 2010 06:36:42 -0400 (EDT)

Attributes[Function]

{HoldAll,Protected}

Since Function has the attribute HoldAll, you need to use Evaluate

listp = {a, b, c, d, e, h, j};

ll = d + a x + h x^2 + b y + e x y + c z + j z^2;

Function[##, Evaluate[ll]] & @@ {listp}

Function[{a, b, c, d, e, h, j}, 
   a*x + b*y + c*z + d + e*x*y + 
     h*x^2 + j*z^2]


Bob Hanlon

---- Camille <camille.segarra at gmail.com> wrote: 

=============
Dear All,

I am fairly new to mathematica. I am stuck with a problem I cannot solve. I would like to call a previous equation into the function Function. If a type directly the expression or copy paste it, it works. However, when I call the expression by its name it does not.
Here is the code for a more precise explanation:

In: ll
Out: d + a x + h x^2 + b y + e x y + c z + j z^2

In: Function[##, a x + b y + c z + d + e x y + h x^2 + j z^2] & @@ {Listp}
Out: Function[{a, b, c, d, e, h, j}, 
 a x + b y + c z + d + e x y + h x^2 + j z^2]

It works well and I can use it to generate as many equations I want by replacing the variables a,b,c,d,e,h,j.
But if I do:

In:Function[##, ll] & @@ {Listp}
Out:Function[{a, b, c, d, e, h, j}, ll]

And I cannot use it.

Any suggestions?

Thanks in advance. Do not hesitate to post if you need some further information. Sorry for my bad english.

Camille



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