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MathGroup Archive 2004

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Re: Syntax Questions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg50745] Re: [mg50731] Syntax Questions
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sun, 19 Sep 2004 03:55:51 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

With two equations you can only solve for two unknowns; one from each 
equation.  You need two additional equations.

s=Solve[{u1 == a v1+b v2,
          u2 == c v1+d v2},{a,c}][[1]];
T={{a,c},{b,d}} /. s

{{(u1 - b*v2)/v1, (u2 - d*v2)/v1}, {b, d}}


Bob Hanlon

> 
> From: "Dominik Werder" <dwerder at gmx.net>
To: mathgroup at smc.vnet.net
> Date: 2004/09/18 Sat AM 05:48:37 EDT
> To: mathgroup at smc.vnet.net
> Subject: [mg50745] [mg50731] Syntax Questions
> 
> While trying real easy Calculations with mathematica 5 on solaris I  
> encountered difficulties finding the right syntax:
> 
> Here I try solve some equations and write the four resulting variables  
> a,b,c,d into a new matrix T:
> 
> s = Solve[{u1 == a v1 + b v2, u2 == c v1 + d v2}, {a, b, c, d}];
> a = (a /. s)[[1]];
> b = (b /. s)[[1]];
> c = (c /. s)[[1]];
> d = (d /. s)[[1]];
> T = {{a, c}, {b, d}};
> 
> I'm sure this could be done easier, but I dont know how?
> 
> thanks!
> Dominik
> 
> 


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