We get the infima and suprema of the first eigenvalue of the problem\begin{gather*} -y''+qy=\lambda y,\\ \left\{\begin{aligned} y'(0)-k_0^2y(0)=0,\\ y'(1)+k_1^2y(1)=0, \end{aligned}\right.\end{gather*}where \(q\) belongs to the set of constant-sign summable functions on \([0,1]\)such that\[ \int_0^1 q\,dx=1 \text{ or }\int_0^1 q\,dx=-1.\]
@article{212, title = {The Sturm--Liouville problem with singular potential and the extrema of the first eigenvalue}, journal = {Tatra Mountains Mathematical Publications}, volume = {55}, year = {2013}, doi = {10.2478/tatra.v54i0.212}, language = {EN}, url = {http://dml.mathdoc.fr/item/212} }
Karulina, E. S.; Vladimirov, A. A. The Sturm--Liouville problem with singular potential and the extrema of the first eigenvalue. Tatra Mountains Mathematical Publications, Tome 55 (2013) . doi : 10.2478/tatra.v54i0.212. http://gdmltest.u-ga.fr/item/212/