  We consider a Sturm-Liouville operator a with integrable potential $q$ on the
unit interval $I=[0,1]$. We consider a Schr\"odinger operator with a real
compactly supported potential on the half line and on the line, where this
potential coincides with $q$ on the unit interval and vanishes outside $I$. We
determine the relationships between eigenvalues of such operators and obtain
estimates of eigenvalues in terms of potentials.
