This is a bug. Can you open an issue with sympy on GitHub? The correct answer is given if you use exact rational numbers (S(1)/2 or Rational(1, 2)) rather than the float 1/2:
In [6]: solveset(Eq(sin(x), S(1)/2), x, Reals) Out[6]: ⎧ 5⋅π │ ⎫ ⎧ π │ ⎫ ⎨2⋅n⋅π + ─── │ n ∊ ℤ⎬ ∪ ⎨2⋅n⋅π + ─ │ n ∊ ℤ⎬ ⎩ 6 │ ⎭ ⎩ 6 │ ⎭ The problem is that solveset solves this in an overly complicated way using complex numbers even if the domain is reals. Then a small rounding error makes it look like the solutions are not real. -- Oscar On Thu, 5 Oct 2023 at 16:45, Kevin Moore <[email protected]> wrote: > > Hello - I'm trying to use Sympy Live to debug an issue with a program I'm > writing. When I try to use solveset for sin(x)=1/2, I get no solutions. > Apparently it thinks there's a tiny complex portion to the solution. > > Why am I running into this? Ironically I'm not running into this problem in > my own script - maybe it's a version issue? > > Kevin > > > > solveset(Eq(sin(x),1/2),x,S.Reals) > ∅ > > solveset(Eq(sin(x),1/2),x,S.Complexes) > {−i(i(2nπ+0.523598775598299)−1.11022302462516⋅10−16)∣∣n∈Z}∪{−i(i(2nπ−0.523598775598299+π)−1.11022302462516⋅10−16)∣∣n∈Z} > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/c98b1ad9-133b-484d-860a-00c48a7d339en%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAHVvXxSBN89Xhm%2BwWMM9nipP9K1S_U8%2BRi5MCLYqJKO%3DZ%2B76AA%40mail.gmail.com.
