>>>>> "Gunter" == Gunter K?nigsmann <gunter at peterpall.de> writes:
Gunter> I have a problem that clearly is trivial and also states that I am a
Gunter> newbie in many aspects.
Gunter> What I did was
Gunter> k(T)=A+B/T+C/T^2+D/T^3;
Gunter> solve(%,T);
Gunter> After setting A, B, C and D to the right numerical values I hoped one of
Gunter> the solutions would allow me to reconstruct the T if I had a matching k.
Gunter> Unfortunately the results aren't real numbers (like I naively expected)
Gunter> but read like:
Gunter> (1858697.723324983*%i
Gunter> +1516536.685031037)^(1/3)+17920.05777118602/(1858697.723324983*%i
Gunter> +1516536.685031037)^(1/3)+129.4794801195104;
Gunter> I know that (a+b*%i)^(1/3) actually has 3 solutions so maxima cannot
Gunter> unconditionally take any further simplification steps without knowing
Gunter> which of the 3 solutions I need.
Gunter> But if I want to know the only result that is a real number (and am even
Gunter> willing to pick the right solution by hand): Is there any way of telling
Gunter> maxima to tell me how high this number is?
Can you provide an example with values for A, B, C, D, and k? It
looks like k(T) is basically a cubic, and if the coefficients are
real, such a cubic always has at least one real solution.
Ray