Question

When the Eigenvalues are a mixture of real and imaginary values, the PDE is ___________

(a) elliptic-hyperbolic

(b) parabolic

(c) elliptic

(d) hyperbolic

I got this question in an online interview.

I'd like to ask this question from Classification of PDE in section Mathematical Behaviour of Partial Differential Equations of Computational Fluid Dynamics

Answer 1

Correct answer is (a) elliptic-hyperbolic

To explain: When we get a mixed type of Eigenvalues, the type of PDE is also mixed. Many practical equations have mixed behaviour also.