Recent content by Aquinox

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    RFC own vs. provided solution of optics task

    Hia all. I would like to request comments and maybe clarificaions on the task and solutions provided in the attached PDF. It was one of our homework tasks and, IMO the provided solution does not solve the task at hand. I'm currently in a dispute with the chief TA about this and so far...
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    What is the optimal substitution for solving the integral of u^2/(1+u^4)?

    Sorry. The way hinted to me in the paper is that we have to take that t^(-1/2) definition and use fubini's thm. This leads to the aforementioned \int_{0}^{\infty}\frac{u^{2}}{1+u^{4}}du I am perfectly able to integrate the RHS of the equation you've posted, but...
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    What is the optimal substitution for solving the integral of u^2/(1+u^4)?

    That is the answer I, too, have derived from the solutions Mathematica gave me. What I need to know is which method to use to get from the left side to the right side. That is a step non-obvious to me and it has to be.
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    What is the optimal substitution for solving the integral of u^2/(1+u^4)?

    Homework Statement The initial problem is to calculate \int_{-\infty}^{\infty}\cos(x^{2})dx using t=x^{2} and then t^{-\frac{1}{2}}=\frac{1}{\sqrt{\pi}}\int_{-\infty}^{\infty}e^{-tu^{2}}du Homework Equations The Attempt at a Solution I have, by transformation and use of the...
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    Int. Bessel Functions and Equation

    Homework Statement Prove that J_{n}, Y_{n} satisfy x^{2}*y''(x)+x*y'(x)+(x^{2}-n^{2})*y(x)=0 where n\inZ and x\in(R_{>0} Homework Equations The standard definitions of the bessel integrals as given here: http://en.wikipedia.org/wiki/Bessel_Functions The Attempt at a Solution...
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    Calculating uncertainty in data.

    What you are looking for seems to be the variance of measurements. For the std-deviation of the mean value: s_{m}=\frac{s}{\sqrt{n}}=\sqrt{\frac{1}{n(n-1)}\sum_{i=1}^{n}(x_{i}-\bar{x})^{2}} here then holds for n->infinity s_{m}\rightarrow0\; s\rightarrow\sigma with...
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    Electric/Gravitational Forces

    that's a trivial problem asked on electrostatics. Yep, you divide it for a ratio.
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    What is the 1D Fourier transform of the function e^{-\lambda x^{2}}?

    Why though? The way known to me to diagonalize a symmetric matrix is TAT^-1 = D with orthogonal matrix T. Following is the way I think I've solved it. Taking off from hunt's equation...
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    What is the 1D Fourier transform of the function e^{-\lambda x^{2}}?

    Yep. I've got that hint by a friend yesterday night which led me to: \int e^{-\frac{1}{2}<x,T^{-1}TAT^{-1}Tx>-i<k,T^{-1}Tx>}\Rightarrow\int e^{-\frac{1}{2}<Tx,(TAT^{-1}=D)Tx>-i<Tk,Tx>}\Rightarrow\int e^{-\frac{1}{2}<y,Dy>-i<k',y>}d^{n}y by using that TAT^-1 = D , with D-diagonal. defining...
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    What is the 1D Fourier transform of the function e^{-\lambda x^{2}}?

    Homework Statement Let A be a real, symmetric positively definite nxn - matrix. f:\mathbb{R}^{n}\rightarrow\mathbb{R}\; s.t\;\vec{x}\rightarrow e^{-\frac{1}{2}<\vec{x},A\vec{x}>} Show that the FT of f is given by: \hat{f}(\vec{k})=\frac{1}{\sqrt{\det...
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