       Re: Using results of Solve[simultaneous equations]

• To: mathgroup at smc.vnet.net
• Subject: [mg31083] Re: Using results of Solve[simultaneous equations]
• From: "Allan Hayes" <hay at haystack.demon.co.uk>
• Date: Sun, 7 Oct 2001 03:11:51 -0400 (EDT)
• References: <9pme0e\$64g\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Timie
Two ideas for the first part:

Clear[a,c]:

{a->b,{c:>d}}/.r:Rule|RuleDelayed -> Set;

Definition[a,c]

a = b

c = d

Clear[a,c]
ToSet[(Rule|RuleDelayed)[x_,y_]]:= x=y;
ToSet[z_]:=z;

ToSet//@{a->b,{c:>d}};

Definition[a,c]

a = b

c = d

Second part:

Whether this can be done depends on the values of a and b.
A little further manipulation will be needed in each case.

Clear[a,b]

Eliminate[{a==t, b==t^2+t+1},t]

-1 + b == a + a^2

Solve[{a==t, b==t^2+t+1},b,t]

{{b -> 1 + a + a^2}}
--
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

"Timie Milie" <milstead at cs.bris.ac.uk> wrote in message
news:9pme0e\$64g\$1 at smc.vnet.net...
> I use solve to solve some simultaneous equations and get results of the
form
> a->... b->... c->...
>
> I want to do 2 things:
>     assign each result to an equation of the form a=... b=... c=...
>     so I can then manipulate them...
>
> e.g.
>     display the b result in terms of the result in a
>
> e.g.
>     b = 2 a
>