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How can i use the Solve function to find the actual equation for a

  1. May 4, 2012 #1
    How can i use the Solve function to find the actual equation for a fixed point?
    For the function f(x)=ur(1-u)
     
  2. jcsd
  3. May 5, 2012 #2

    Hepth

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    Gold Member

    Re: Mathematca

    f[u_] := u r (1 - u)
    Solve[f[f] == u, u]

    the u_ means to use it as an input variable, the " := " means not to evaluate it until its used. So i just nested it once, f[f] == u should be the equation for a fixed point of f.
    Solve[EQUATION,VARIABLE] is its use.

    or SOLVE[{EQ1,EQ2},{V1,V2}] for multivariate solutions.

    I assume "u" was the variable in this case as f(x) = u r (1- u) has no x in it.
     
  4. May 5, 2012 #3
    Re: Mathematca

    why have you done f[f==u and not f==u?
    is this because then it also gives the complex solutions?
     
  5. May 5, 2012 #4

    Hepth

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    Gold Member

    Re: Mathematca

    Ah that was a mistake. I was thinking of attractive fixed point functions.

    Yeah Solve[f==u,u] should be enough. It will give all solutions, include any complex ones.
     
  6. May 5, 2012 #5
    Re: Mathematca

    Thanks for clearing that up, because i was getting confused
     
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