\int\limits_{ - \varepsilon }^\varepsilon { - \frac{{{\hbar ^2}}}{{2m}}\frac{{d{{\kern 1pt} ^2}\psi (x)}}{{d{\kern 1pt} {x^2}}}dx} + \int\limits_{ -    \varepsilon }^\varepsilon {\lambda \delta \left( x \right)\psi (x)} dx = \int\limits_{ - \varepsilon }^\varepsilon {E\psi (x)dx} .