I'm trying to evaluate this integral

the answer should be 1. I keep getting zero. Anyone able to get 1?

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Posts: 6767

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Posts: 2836

picture isn't working for me. Try reposting, or try wolframalpha, it can show you step by step. Cramster and hot math are also good, but only if its from a book, and you have to pay (or find someone who did)

Posts: 1380

Pic didn't show up for me but... Its summer and math is illegal

Posts: 860

pm me

Posts: 814

I would just look up how to do it on youtube thats how i did all of my homework last year

Posts: 6767

Posts: 1380

I hope I never have to do that

Posts: 3601

What kind of math is this OP?

Posts: 504

damn! why did africa do this to me>?

Posts: 2

If you haven't figured it out yet, i don't think the conjugate should be
equal. In addition, you mixed up the change to b in the constant out
front. With those two the imaginary part drops and you end up with 1.

Posts: 6767

uh I don't really know. hence the frustration. It's for quantum physics but this is just a math/statistics problem. I have seen this kind of stuff in statistics but not with integrals like this. I just multiplied psi by its complex conjugate and am trying to integrate that over the interval (-infinity,infinity). However when I used integration for parts I get zero, and to be normalized it should be equal to one.

also for anyone trying to follow what I did. the integration in red from dv to v is correct I think. I just used an antiderivative I found on the wikipedia page for the error function.

However I just stumbled across the wikipedia page for gaussian integrals and the first paragraph mentions its applications in quantum field theory, which is a class that my prof teaches, so I might have a lead haha.

anyways it's gonna be an all nighter for sure. Last time I asked for homework help on NS you guys all killed it so I thought I'd try again

also for anyone trying to follow what I did. the integration in red from dv to v is correct I think. I just used an antiderivative I found on the wikipedia page for the error function.

However I just stumbled across the wikipedia page for gaussian integrals and the first paragraph mentions its applications in quantum field theory, which is a class that my prof teaches, so I might have a lead haha.

anyways it's gonna be an all nighter for sure. Last time I asked for homework help on NS you guys all killed it so I thought I'd try again

Posts: 6767

really? why is the conjigate not equal? the imaginary part dropping would be exactly what I want!

if I messed up the conjigate i'm going to be so mad!

+K

if I messed up the conjigate i'm going to be so mad!

+K

Posts: 2

in the conjugate the imaginary part becomes negative

Posts: 2025

^^ yeah he has it.

http://en.wikipedia.org/wiki/Complex_conjugate

In your Y*, the complex number change to negative, when you do Y*xY your Im part goes out.

Y*=(...)x(e^-ikx)x(...)

Y =(...)x(e^ikx)x(...)

YxY* = (...)^2x(..)^2 = [(b/Pi)^1/2] x [e^-bx^2]

Primitive of [e^-bx^2] is [(Pi/b)^1/2], so in the end you have 1

Posts: 6767

Thanks everyone. It was that I messed up the complex conjugate. I couldn't see why until I used euler's formula and then it is easy to see how the complex part cancels and the integration becomes much easier!

+K to all of you who helped out. We can let this die and get the math off the page before the kids wake up in the morning haha.

+K to all of you who helped out. We can let this die and get the math off the page before the kids wake up in the morning haha.

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