In the paper Fully Homomorphic Encryption over the Integers in the introduction:
How do I calculate $r$ and $q$ of this equation in the picture?
$r \approx 2^{\sqrt{\eta}}$ and $q \approx 2^{\eta^3}$
what is the meaning of symbol like $\eta$ in the picture?
$p\in [2^{\eta-1},2^\eta)$
and how calculate it?