Thanks to visit codestin.com
Credit goes to dlmf.nist.gov

About the Project
28 Mathieu Functions and Hill’s EquationMathieu Functions of Integer Order28.7 Analytic Continuation of Eigenvalues
Figure 28.7.1 (See in context.)
See accompanying text
Figure 28.7.1: Branch point of the eigenvalues a0(iq^) and a2(iq^): 0q^2.5.