Another identity among squares of eigenfunctions
Robert L. Sachs · Journal of Mathematical Physics · 1986
A variant of an identity of H. P. McKean and E. Trubowitz [Commun. Pure Appl. Math. 29, 143 (1976)] for Hill’s equation is derived via contour integration. The identity is 1=∑∞j=0(−1) j‖y2(1, λij) ‖ ⋅ f2j(x).