Thanks Barton. That solved my specific problem nicely. A couple more
things FYI below.
On Thu, 24 Jul 2008, Barton Willis wrote:
> The function to_poly_solve tries to be careful; try this (eq is your
> equation) workaround:
>
> (%i3) to_poly(eq,[phi2])$
> (%i4) elim(first(%),[%g0,%g1])$
(The dummy variables I get seem to be called %g1 and %g2, but I guess
this difference is trivial.)
> (%i11) for si in sol do print([si,radcan(subst(si, eq))]);
> <radcan believes in the multi-valueness of sqrt, so all solutions are OK>
Nice. But I wonder what I should read into it if one of the solutions
didn't pass this test.
> So to_poly_solve finds two solutions; depending on some messy
> inequality, conditionally there is a third solution.
Almost. There are also chains of answers (e.g. -+---+--) for which
to_poly_solve finds only one solution, or (e.g. -+-0) for which it
finds no solution at all.