On the Martin-Newton Condition for Finite-Dimensional Unitary Matrices
Cornel Eftimiu · Journal of Mathematical Physics · 1971
A prescription is formulated by means of which one can write conditions for the existence of solutions of a nonlinear system expressing the unitarity of n × n symmetric matrices. These conditions are less restrictive than those analog to the Martin-Newton condition for the nonlinear integral equation representing the unitarity condition in the elastic region. At least for n ≤ 4 these conditions are also necessary.