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I am trying to solve an equation for a variable t under some assumptions.

However, the output produced is completely unclear to me. In particular, Mathematica's output says "Assuming a list of rules" and contains stuff like "#1^6 &" which I can't interpret (even though I understand the operators in general). Can anyone help? The expression I am trying to evaluate is as follows:

Assuming[
  omega == 2 && sigma > 0 && sigma <= 1 && t > 0 && t <= 0.5 && 
    sigma ∈ Reals && omega ∈ Reals && t ∈ Reals,
  Solve[
    (omega*sigma*(1/(omega*(t - 1)) + 1) - (sigma*t)/(t - 1)^2)/
        (omega*sigma*t*(1/(omega*(t - 1)) + 1) + 1) - t/(t - 1)^2 -
      1/(t - 1) - omega + log (omega*sigma*t*(1/(omega*(t - 1)) + 1) + 1)*
        (omega*sigma*(1/(omega*(t - 1)) + 1) - (sigma*t)/(t - 1)^2) +
      omega*(1/(omega*(t - 1)) + 1) -
      2*omega^2*sigma*t*(1/(omega*(t - 1)) + 1)^2 +
      (2*omega*sigma*t^2*(1/(omega*(t - 1)) + 1))/(t - 1)^2 == 0,
    t]]

Any help would be very appreciated.

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    $\begingroup$ Have you seen this? Let me also offer a tip: anything you see in your output that you don't understand, highlight it and press F1. $\endgroup$
    – J. M.'s missing motivation ♦
    Commented Sep 30, 2017 at 14:40
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    $\begingroup$ Your output involves Root objects. Think of them as a generalization of radicals, capable of representing any algebraic number. $\endgroup$
    – John Doty
    Commented Sep 30, 2017 at 14:42
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    $\begingroup$ Root[polynomial,n] is essentially the same kind of thing as Sqrt[x], but generalizes to cases where radicals can't go. $\endgroup$
    – John Doty
    Commented Sep 30, 2017 at 15:08
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    $\begingroup$ Also, did you mean to use log as a variable? The logarithm is Log[], using brackets, not parentheses. $\endgroup$
    – John Doty
    Commented Sep 30, 2017 at 15:10
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    $\begingroup$ Another tip for you. Since you're now (somewhat) familiar with Root[], look at the degree of the polynomial in its first argument. If it's 5 or greater, don't count on getting anything more explicit than that, per Abel and Galois. $\endgroup$
    – J. M.'s missing motivation ♦
    Commented Sep 30, 2017 at 15:35

1 Answer 1

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  1. Mathematica has transformed your problem into finding the roots of a polynomial of degree 6 in t, which has 6 solutions. As always, it returns the solutions as a list of rules. In this case, each of the solutions is expressed as a Root object, because equations of degree 6 can usually not be solved in terms of radicals.

    See Root in the documentation.

  2. One of your terms is 

    log (omega*sigma*t*(1/(omega*(t - 1)) + 1) + 1)*
  (omega*sigma*(1/(omega*(t - 1)) + 1) - (sigma*t)/(t - 1)^2)

    The symbol log is being interpreted as a complex number. Is that intentional? Or were you trying to write an expression of form Log[...]? If the latter, then you problem is a simple syntax error.

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  • $\begingroup$ Thanks for your reply! No, it wasn't intentional. However, when I replace log by "Log[...]", the problem persists... $\endgroup$
    – Alex Held
    Commented Oct 1, 2017 at 20:45

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