Why can we write this? (maths)

[atomqwerty]

Hi,

why can we write the relation of the image


http://img413.imageshack.us/i/formulal.jpg/


(Where it says 'La integral de corriente es...')

Thank you!

[Dickfore]

Integration by parts.

[Chopin]

Integration by parts.

Along with the fact that \Psi goes to 0 at infinity.

[Fredrik]

Most of the details can be found in this thread (http://www.physicsforums.com/showthread.php?t=457334).

[atomqwerty]

Thanks to all!