why in the problem of dirac delta potential, the integral(adsbygoogle = window.adsbygoogle || []).push({});

[tex]\int^{\epsilon}_{-\epsilon}\phi''(x)dx[/tex] is equal to [tex]\phi'(\epsilon)-\phi'(-\epsilon)[/tex]???

but [tex]\int^{\epsilon}_{-\epsilon}\phi(x)dx[/tex] is equal to 0

if, for example[tex]\phi(x)=e^x[/tex]

then [tex]\phi(x)''=\phi(x)[/tex]

but, the firts integral is [tex]e^{\epsilon}-e^{-\epsilon}[/tex]

and the second integral would be to zero

i dont understand

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# Dirac delta potential

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