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How to use solve function in matlab in this case

  1. Oct 26, 2007 #1
    We are trying to find the roots of a function where exp(f(z)) = c. (where c is a complex number). Also f(z) is a polynomial function. The function will have the following format:
    expsolve( [an an-1 …] , c ) where n is the degree of “z”.
    For do this I took the natural logarithm of both sides and find f(z) = log(c). The code I have written so far is as follows;

    function expsolve(v,c);
    len=length(v)
    temp=log(c);
    syms z;
    syms def;
    syms first;
    first=0;
    for(a=1:len)
    def=v(len-a+1)*(z^(a-1))
    first=first+def
    end
    first
    equ=first-log(c)

    --------------------
    now if I write expsolve([1 5 3], 4) for instance
    until the first part it gives me the correct result (first=z^2+5*z+3)
    however, I could not do the rest. how can I find the roots of first-log(c).

    I tried to write different combination of :
    solve('equ=0','z').
    However, it gave my either an error or a illogical answer.

    How can I proceed in this question. Besides the code I have written is there any simpler way to solve the question?
     
  2. jcsd
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