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Re: Simple question from a biologist

  • To: mathgroup at smc.vnet.net
  • Subject: [mg67151] Re: Simple question from a biologist
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Sun, 11 Jun 2006 02:16:57 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <e6e27d$1tp$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

tnad wrote:
> I'm a bit new to this so please bear with me. I solved this eqation:
> 
> Sol = Solve[{{{-x, 0, z}, {x, -y, 0}, {0, y, -z}}.{A, B, C} == 0, A + B + C == 1}, {A, B, C}]
> 
> and got the ouputs of A, B and C interms of x,y, and z each.
> 
> Now I want to express a term called "rate" where rate = Ax = By = Cz in terms of x, y and Z only.
> 
> So I tried to do this:
> Solve[rate == Ax , rate] /. Sol
> 
> but I cannot get the rate in terms of x,y and z.
> Is there a better way to do this? Also if someone knows of a better tuttorial (better than the built-in tuttorial) for mathematica, please let me know.
> 
Do you mean something like Out[2]?

In[1]:=
sol = Solve[{{{-x, 0, z}, {x, -y, 0}, {0, y, -z}} . {A, B, C} == 0,
     A + B + C == 1}, {A, B, C}]

Out[1]=
              y z                   x z
{{A -> ---------------, B -> ---------------,
        x y + x z + y z       x y + x z + y z

               x y
    C -> ---------------}}
         x y + x z + y z

In[2]:=
Solve[rate == A*x, rate] /. sol[[1]]

Out[2]=
                x y z
{{rate -> ---------------}}
           x y + x z + y z


HTH,
Jean-Marc


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