Function Definition and 1000 Threads

  1. danielhaish

    I Why quantum wave function collapse is not consider a signal?

    I read about the non-communication theorem and I understand why when changing one practical will not change the other . But suppose that there is two observers that doing the double slit experiment, but using it with two entanglement practicals. observer one should send signal of yes or...
  2. T

    Finding the wave function when given the momentum eigenstate

    For part a, I have the following $$\ket{p_0} = \varphi_{p_0}(x)=\frac{1}{\sqrt{2\pi\hbar}}e^{ip_0x/\hbar}$$ but I am totally lost on how to proceed.
  3. I

    I Complex Conjugate of Wave Function

    I've been studying quantum mechanics this semester in school and have ran into an issue I can't find an answer for. I understand why we take the complex conjugate of the wave function, such as when calculating expectation values. I'm a little confused though as to why we take the complex...
  4. Hamiltonian

    Velocity of a cart moving in the rain as a function of time

    At time t = 0, the mass of the cart is ##M_0## and velocity is ##v_0## in a time interval ##dt## let a mass of ##dm## be added to the cart due to the pouring water and let the reduction in speed be ##dv## ##\lambda = dm/dt## applying conservation of momentum from the ground frame gives $$M_0...
  5. D

    A multivariate function of Toruses - tangent vectors

    Thank you to all those who helped me solve my last question. This week, I've been assigned an interesting problem about toruses. I think I've solved most of this problem on my own, but I'd like to hear a few suggestions for part c. I think this map multiplies tangent vectors by a factor of...
  6. MidgetDwarf

    Is the given function continuous at x= 0? f(x) = {sin(1/x) if x≠0, 1

    I know that the function, g(x)= sin(1/x) has infinite oscillations when the values of x get closer and closer to 0. So its limit does not exist (from graphing it). However, the way that we defined f(x), at x=0, f(x)=1, but f(x)= sin(1/x) on (0,infinity). I have an issue in general showing that...
  7. SchroedingersLion

    A Derivative of norm of function w.r.t real-part of function

    Greetings, suppose we have ##h(u)=\frac{1}{2} \left\|Au-b \right\|_{2}^2## with ##A## a complex matrix and ##b,u## complex vectors of suitable dimensions. Write ##u=u_1 + iu_2## with ##u_1## and ##u_2## as the real and imaginary part of ##u##, respectively. Show that ##\frac {\partial h}...
  8. Theia

    MHB Computing the value of sine function accurately

    Hi all Simple question: How I can compute the value of \(a = \sin \left( 2017 \sqrt[5]{2} \right) \) under following assumptions: No use of advanced numerical libraries is allowed. Only accepted operations are: comparisons, absolute value, addition, subtraction, multiplication and division...
  9. omegax241

    A strange wave function of the Hydrogen atom

    I am trying to solve the following exercise. In a H atom the electron is in the state described by the wave function in spherical coordinates: \psi (r, \theta, \phi) = e^{i \phi}e^{-(r/a)^2(1- \mu\ cos^2\ \theta)} With a and \mu positive real parameters. Tell what are the possible values...
  10. D

    Inverse of a multivariate function

    Any help with this introductory differential geometry HW would be greatly appreciated. My attempt at solving the first problem: y=4x^3-3x has the derivative 12x^2-3, which is 0 when x^2=(1/4). {x^2=(1/4)} is the singular set, and the inverse is defined for everywhere except F({x^2<(1/4)}). the...
  11. A

    MHB Dstermine the equation of function

    The equation of the axis of symmetry of the graph of a quadratic function is x=-1. The graph passes through the points (0,3) and (-3, 9). Determine the equation of the function.
  12. Athenian

    2D Steady-state Temperature in a Circular Plate - Bessel Function

    I learned about Bessel functions and steady-state temperature distributions in the past. Recently, I was searching online for some example problems on the topic and found the "original question" along with the solution online as a PDF file. While I am unsure will it be appropriate for me to...
  13. Hercuflea

    I Solar flare: Help normalizing the Band function

    I am trying to understand how to normalize a proton energy spectrum from a solar flare. The spectrum is given by the Band Function, and I cite the paper "Spectral Analysis of the September 2017 Solar Energetic Particle Events" by Bruno in 2019, link to paper. The equation number in the paper is...
  14. H

    MHB Double summation: inner index = function of outer index

    Here N, a, and b are integer constants. M is also an integer but changes for every value of x, which makes the index of the second summation dependent on the first. The problem is the relationship M(x) is analytically difficult to define. Is there a way to solve/simplify this expression?
  15. F

    I Why QFT still goes well while it lacks the notion of wave function?

    In QM by virtue of wave function we calculate any things. But in QFT it seems that there is a lacking of notion of wave function.I do not understand why QFT still goes well(it is a good theory to calculate any things)?
  16. Z

    Delta function for \nabla(log s), where s = \sqrt{x^2+y^2}

    My intuition for this problem is to use divergence theorem: ## \int_V \nabla^2 u dV = \int_S \nabla u \cdot \vec{n} dS## But note that ##\vec{n}## is perpendicular to x-y plane, and makes ##\int_S \nabla \ln s \cdot \vec{n} dS = 0## If we take laplacian in polar coordinate directly, then...
  17. F

    A Don't understand this function, s(cosξ + j sinξ) in my textbook

    My textbook for Advanced Electomagnetics, by Balinas has this identity. cos θ = se^(jξ) = s( cos ξ + j sin ξ ). I have no idea what they are saying. Is there an S funtion I'm not aware of? I've looked back and forth, and he doesn't seem to explain it's use. I've inserted a picture of the...
  18. S

    B Domain of a composite function

    ##f(x)=-x^2 + 3## so ##f^{-1} (x)=- \sqrt{3-x} ~, x \leq 3## ##ff^{-1} = - (- \sqrt{3-x})^2 + 3 = x## and the domain will be ##x \leq 3## ##f^{-1} f = - \sqrt{3-(-x^2+3)} = -x ## and the domain will be ##x \leq 0## My question: ##ff^{-1} (x)## or ##f^{-1} f(x) ## is not always equal to...
  19. newjerseyrunner

    I How Do You Reverse a 2.5D Projection Function in Programming?

    I have this function that I need to reverse. I can't figure out how to reverse it though, I should be able to take the resulting int, put it through a function with the height value and get back distance. Normally, when I get stuck, I just ask wolfram alpha to solve it for me, but that...
  20. K

    Photoelectric effect and continuous energy function

    E=hf-W where W is a work function. However we know that electrons in an atom will be excited only when radiated with photons of n*f0 discrete number of frequencies. where E=hf-W is a continuous function. Is this because energy level is continuous within a conductor? If we think of only...
  21. Antarres

    A Dirac delta function confusion

    As a part of a bigger problem, I was trying to evaluate the D'Alambertian of ##\epsilon(t)\delta(t^2-x^2-y^2-z^2)##, where ##\epsilon(t)## is a sign function. This term appears in covariant commutator function, so I was checking whether I can prove it solves Klein-Gordon equation. Since there's...
  22. H

    Method of image with Green function

    A conducting sphere of radius a is made up of 3 different shells, upper part a/2 z -a/2, the middle part -a/2 z a, the lower part -a z -a/2 where the center of the sphere is at the origin. The upper part V and the lower part has -V potentials, while the mid part is grounded. Find the...
  23. Sabertooth

    I Elliptic Function Rotation Problem

    Hi all:) In my recent exploration of Elliptic Function, Curves and Motion I have come upon a handy equation for creating orbital motion. Essentially I construct a trigonometric function and use the max distance to foci as the boundary for my motion on the x-plane. When I plot a point rotating...
  24. AN630078

    Photoelectric Effect Graph and Work Function Questions

    1. a)I have plotted the graph on desmos and attached an image here. b i. The threshold frequency is equal to the x-intercept ~ 5.6*10^14 Hz ii. The work function is equal to the y-intercept ~ -3.75*10^19 J (would it be correct to state that this value is negative?) c. Convert to eV; 3.75*10^19...
  25. K

    Atmospheric pressure as a function of altitude

    Summary:: i) Set up a differential equation that describes how the pressure ##p## varies with the distance r from the center of the planet. Hint: You can base your reasoning on static equilibrium and Archimedes' principle. ii)Calculate how the atmospheric pressure p and the density of the...
  26. B

    Is the Function Analytic? Testing the Cauchy Riemann Equations

    I tested the first function with the Cauchy Riemann equations and it seemed to fail that test, so I don't believe that function is analytic. However, I'm really not sure how to show that it is or is not analytic using the definition of the complex derivative.
  27. S

    Probability of a state given the partition function

    If my partition function is for a continuous distribution of energy, can I simply say that the probability of my ensemble being in a state with energy ##cU## is ##e^{-\beta cU} /Z##? I believe that isn't right as my energy distribution is continuous, and I need to be integrating over small...
  28. A

    Determining the domain and range for the function ##f^{-1}##

    The domain and range of this function will be the same. We can let ##𝑓(𝑥)=\sqrt{x},𝑥≥0## However, ##𝑦=𝑓(𝑥)≥0##, so the domain and range of ##f## are ##[0,+∞)## And since ##f## is a function, ##f^{-1}s## domain is the range of ##f## and ##f^{-1}s## range is ##f’s## domain. In other words...
  29. StevieTNZ

    B "Test of wave function collapse suggests gravity is not the answer"

    https://phys.org/news/2020-09-function-collapse-gravity.html An interesting article I saw yesterday. However, both Nature articles (the summary [https://www.nature.com/articles/s41567-020-1026-2] and the actual technical paper [https://www.nature.com/articles/s41567-020-1008-4]) are behind a...
  30. anemone

    MHB Maximum and minimum of a function

    Let $a$ be an integer. Consider the function $y=\dfrac{12x^2-12ax}{x^2+36}$. For what integral values of $a$ the maximum and the minimum of the function $y=f(x)$ are integers?
  31. K

    Show that a (1,2)-tensor is a linear function

    I know that a tensor can be seen as a linear function. I know that the tensor product of three spaces can be seen as a multilinear map satisfying distributivity by addition and associativity in multiplication by a scalar.
  32. tomdodd4598

    I QED - running of coupling (beta function)

    Hey there, I am a little confused about the way most textbooks and notes I've read find the beta function for QED. They find it by looking at how the photon propagator varies with momentum ##q##, in particular in the context of a ##2\rightarrow2## scattering process which is proportional to...
  33. madafo3435

    Help please with this integral involving an inverse trig function

    ## \int_0 ^ {2 \pi} \frac {dx} {3 + cos (x)} ## las únicas formas que probé fueron, multiplicar por ## \frac{3-cos (x)}{3-cos (x)} ## pero no me gusta esto porque obtengo una expresión muy complicada. También recurrí a la sustitución ## t = tan (\frac {x} {2}) ## que me gusta bastante, pero...
  34. T

    Determine if a function is strictly increasing/decreasing

    Hi there. I have the following function: $$f(x)=x+\frac{1}{(x+1)}$$ I've caculated the derivative to: $$f'(x)=1-\frac{1}{(1+x)^2}$$ And the domain to: $$(-\infty, -1)\cup(-1, \infty)$$ I've also found two extreme point: $$x=0, x=-2$$ I know that a function is strictly increasing if...
  35. M

    Finding a function given a limit and restriction

    Not sure how to go about this. Would relying on a hole or asymptote work?
  36. T

    Do strategy games and real time strategy games improve brain function?

    Hi, just wanting to know the answer to this. What parts of the brain do playing these games stimulate? What effects do playing these games have on the brain? what brain functions do they improve or strengthen? more specifically I mean the games call to power 1 and/or empire Earth 1. Note that i...
  37. A

    MHB How can i integrate this function

    \[ \int_{0}^{\inf} \frac{e^{-\frac{(x-a)^2}{b}}}{x^2-c^2} dx\] or \[ \int_{0}^{constant} \frac{e^{-\frac{(x-a)^2}{b}}}{x^2-c^2} dx\] maybe application Residue theorem integral ? because this problem same the kramers kronig relation?
  38. notaphysicsmajor79

    Brain function & bipolar: fluid volume & speed of information in tubes

    This is a long post with limited amount of physics in it (but it is a physics question, so hopefully it is allowed). I am a scientist but trained as an ecologist (PhD) and despite my long interest in physics, my knowledge of it remains rather rudimentary. Apologies for that, in advance. I am...
  39. F

    Python Python IDLE and print function....

    Hello, While using the IDLE editor, I noticed that it is possible to simply type the variable name, list name, dict name and view its content without using the print() function...For example, if the variable a=5, then I would expect print(a) to output 5. And it does. But I can also simply type...
  40. S

    B The terminology "G is only a function of...."

    If we have a set of variables ##x_1, x_2, ...x_n ## what does it mean to say that "##G## is only a function of ##x_1,x_2,x_3##"? My thoughts: Context 1: The function ##G## has been previously defined. In Context 1, saying "##G## is only a function of ##x_1,x_2,x_3##" means the same thing as...
  41. Monoxdifly

    MHB Determining c in Quadratic Function Turning Point

    The graph's turning point of a quadratic function f(x)=ax^2+bx+c is over the X-axis. If the coordinate of the turning point is (p, q) and a > 0, the correct statement is ... A. c is less than zero B. c is more than zero C. q is less than zero D. q equals zero Since the point (p, q) is over the...
  42. Frigus

    B Why the derivative of area is related to the graph of the function

    the explanation about the question I got from internet is, A very small change in area divided by the dx will give the function of graph so anti-derivative of function of graph should be equal to the area of the function. It also seem quite obvious to me but I am not satisfied by it, It seems to...
  43. M

    Engineering Fourier Transform: best window to represent function

    Hi, I was hoping to gain more insight into these window questions when looking at frequency spectra questions. I don't really know what makes windows better than one another. My attempt: In the question, we have f(t) = cos(\omega_0 t) and therefore its F.T is F(\omega ) = \pi \left(...
  44. Wrichik Basu

    MATLAB Using repmat to plot a periodic function

    Consider the following function: $$f(x) = \begin{cases} 1 & \text{when} & -\pi<x<0\\ 0 & \text{when} & 0<x<\pi \end{cases}$$ Beyond ##-\pi## and ##\pi##, the function just repeats itself; it is periodic. I want to plot this function for values beyond ##-\pi## and ##\pi##. The graph should look...
  45. M

    Is the change in internal energy really a state function?

    Here is the figure: The answer is $$Q_A<Q_B$$ which I can show by calculation using the above equations. What's confusing to me is I thought that the change in internal energy was a state function. Which would mean since the initial and final points are the same, $$\Delta E_A=\Delta E_B$$ or by...
  46. J

    The collapse of the wave function?

    I never took any physics courses nor don't have a background in mathematics never the less I became very interested in quantum physics after reading Sean Carroll's book Something deeply hidden. One of the difficult things for me to wrap my head around was the concept of superposition and...
  47. Y

    C/C++ I cannot get the size of the array after passing it to a function in C++

    I have a strange problem. I pass an Array[20] to a function. When I put cout << sizeof(Ar); (line 29 in the program) it only shows the length of one element ( 4bytes). BUT if I write cout << Ar[10]; (line 30 in the program) It will give me the correct number of the original idNum[10]. I tried a...
  48. Neothilic

    I How to find the moments using the characteristic function?

    I have the characteristic function of the Cauchy distribution ##C(t)= e^{-(\mid t \mid)}##. Now, how would I show that the Cauchy distribution has no moments using this? I think you have to show it has no Taylor expansion around the origin. I am not sure how to do this.
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