Why can we write this? (maths)

[atomqwerty]

Hi,

why can we write the relation of the imagehttp://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.

 

[atomqwerty]

Thanks to all!