Recent content by FatPhysicsBoy
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Unitary translation operator and taylor expansion
Ooooooooooooooooooooooooooooooooooooooooooooooohhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh! :D Oh! :D Oh my lord okay I understand :D That is an insanely good explanation thanks so much! :D I guess because it is a show that question too it is clear from the result that one should expand in...- FatPhysicsBoy
- Post #10
- Forum: Advanced Physics Homework Help
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Unitary translation operator and taylor expansion
Hi Bruce, so if we look at the terms either side of the first equals sign I see that as the definition of 'expanding ##f(x)## around the value ##x=x_0##. So using that 'definition', if we wanted to say 'what does ##f(x)## look like around ##x=z##?' we'd substitute ##x_0 = z## right? Where I've...- FatPhysicsBoy
- Post #8
- Forum: Advanced Physics Homework Help
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Unitary translation operator and taylor expansion
See, reading this again in the context of what I posted earlier just reaffirms the thing I'm confused about. If I read your first sentence I can see why we have the ##x_0##'s and ##\delta a##'s where they are on the rhs of 3) but then if I try to think of a 'variable transformation' which...- FatPhysicsBoy
- Post #6
- Forum: Advanced Physics Homework Help
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Unitary translation operator and taylor expansion
Thanks for the replies! :) Why are we looking at what's happening to ##f(x_0-\delta a)## around ##x_0##. It's just confusing because if we had ##f(x)## and we wanted to expand about a point ##x=x_0##.. I guess I'm confused because in 1) ##x_0## doesn't appear on the left hand side, but all...- FatPhysicsBoy
- Post #4
- Forum: Advanced Physics Homework Help
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(Algebra) Quantum Theory - Cauchy-Schwartz inequality proof
Anyone? Parts 1) and 2) can pretty much be ignored they just provide context for the problem.. I think ultimately it's just a complex number/conjugation question which I haven't understood properly.- FatPhysicsBoy
- Post #2
- Forum: Advanced Physics Homework Help
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Why do integrals featuring Dirac deltas equate to certain values?
Seriously, thanks for the help! I've got another question I've just posted over in advanced physics on the taylor expansion if you fancy it! :)- FatPhysicsBoy
- Post #12
- Forum: Calculus and Beyond Homework Help
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Unitary translation operator and taylor expansion
Homework Statement I have quite a straightforward question on the taylor expansion however I will try to provide as much context to the problem as possible: ##T(a)## is unitary such that ##T(-a) = T(a)^{-1} = T(a)^{\dagger}## and operates on states in the position basis as ##T(a)|x\rangle =...- FatPhysicsBoy
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- Expansion Operator Taylor Taylor expansion Translation
- Replies: 10
- Forum: Advanced Physics Homework Help
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Why do integrals featuring Dirac deltas equate to certain values?
Apologies that's what I meant, that the 'area' is then just 1 scaled by the 'area' of ##g(u)##. Thanks for all your help guys!- FatPhysicsBoy
- Post #10
- Forum: Calculus and Beyond Homework Help
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Why do integrals featuring Dirac deltas equate to certain values?
Is this because, ##\delta(x-u)## is a delta function centered on u? Is it sort of like an orthonormal function where if we turn the integral into a sum along ##x## then the only place where ##\delta(x-u)dx## is non-zero is at ##x=u##? So if we're essentially summing over ##\delta(x-u)g(u)## then...- FatPhysicsBoy
- Post #8
- Forum: Calculus and Beyond Homework Help
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Why do integrals featuring Dirac deltas equate to certain values?
##\int_\infty^\infty \delta(u-u_0)f(u-a)du = f(u_0 - a)## I still don't understand? So ##\int_\infty^\infty \delta(x-u)f(x-a)dx = f(-u-a) = f(-x-2a)## I think I'm seriously missing something :S- FatPhysicsBoy
- Post #5
- Forum: Calculus and Beyond Homework Help
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Why do integrals featuring Dirac deltas equate to certain values?
I don't follow? Why do I do this and also I don't understand, so I have ##\int^{\infty}_{\infty}\delta(x-u)g(u)du## but ##x=u## means I have ##\delta(0)##?- FatPhysicsBoy
- Post #3
- Forum: Calculus and Beyond Homework Help
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Why do integrals featuring Dirac deltas equate to certain values?
Homework Statement Having trouble understanding dirac deltas, I understand what they look like and how you can express one (i.e. from the limiting case of a gaussian) but for the life of me I can't figure out why the results of some integrals featuring dirac deltas equate to what they do...- FatPhysicsBoy
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- Delta Dirac Dirac delta
- Replies: 11
- Forum: Calculus and Beyond Homework Help
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(Algebra) Quantum Theory - Cauchy-Schwartz inequality proof
Homework Statement Given two arbitrary vectors |\phi_{1}\rangle and |\phi_{2}\rangle belonging to the inner product space \mathcal{H}, the Cauchy-Schwartz inequality states that: |\langle\phi_{1}|\phi_{2}\rangle|^{2} \leq \langle\phi_{1}|\phi_{1}\rangle \langle\phi_{2}|\phi_{2}\rangle...- FatPhysicsBoy
- Thread
- Algebra Inequality Proof Quantum Quantum theory Theory
- Replies: 1
- Forum: Advanced Physics Homework Help
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Graduate Error propagation for a sum of means
Ultimately all the power is in my hands at the moment since everything we are discussing is in-fact being done in simulation. We have the full spherical detector geometry and can run events as and when and where we like through monte carlo. I think this method has broken down for the reasons you...- FatPhysicsBoy
- Post #9
- Forum: Set Theory, Logic, Probability, Statistics
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Graduate Error propagation for a sum of means
Thank you for your help Stephen, I will compute the variances using the method you suggested. I understand, this is supposed to be the first stage though. See how far we can go using chi-square and possibly replace this method with a likelihood method or some other determining method. The aim...- FatPhysicsBoy
- Post #7
- Forum: Set Theory, Logic, Probability, Statistics