The NIEP for four dimensional Leslie and doubly stochastic matrices with zero trace from the coefficients of the characteristic polynomial

The constraints on the coefficients of the characteristic polynomials of four dimensional doubly stochastic matrices with zero trace and Leslie stochastic matrices with zero trace are determined. Then, on the basis of these constraints, the regions of the complex plane consisting of those points which can serve as characteristic roots of four dimensional doubly stochastic matrices with zero trace and Leslie stochastic matrices with zero trace are characterized.