Function Definition and 1000 Threads

  1. T

    What is the significance of the grand partition function in an Einstein solid?

    $$Q_{(\alpha, \beta)} = \sum_{N=0}^{\infty} e^{\alpha N} Z_{N}(\alpha, \beta) \hspace{1cm} (3.127)$$ Where ##Q## is the grand partition function, ##Z_N## is the canonical partition function and: $$\beta = \frac{1}{kT} \hspace{1cm} \alpha = \frac{\mu}{kT} \hspace{1cm} (3.128)$$ In the case of an...
  2. R

    I How do you normalize this wave function?

    I have a basic question in elementary quantum mechanics: Consider the Hamiltonian $$H = -\frac{\hbar^2}{2m}\partial^2_x - V_0 \delta(x),$$ where ##\delta(x)## is the Dirac function. The eigen wave functions can have an odd or even parity under inversion. Amongst the even-parity wave functions...
  3. ?

    I Are there any two pairs of integers with the same result in a specific function?

    Hello all, This is a problem of a different flavour from my usual shenanigans. I'm looking at a function $$f(m,n)=\frac{m^2n^2}{(m+n)(m-n)}$$ and am trying to determine if there are any two pairs of values ##(m_1,n_1)## and ##(m_2,n_2)## which evaluate to the same result. Assume that...
  4. Luke_Mtt

    I Calculate a spin state as a function of the base spin states

    Practically it is said that, given two spin states |u⟩ (up) and |d⟩ (down) - which are the spin measured along the +z and -z semiaxes - such that they are orthogonal ( ⟨u|d⟩ = ⟨d|u⟩ = 0), it is possible to write any other spin states using a linear combination of these two (because they are a...
  5. G

    MHB Finding minimum value of function with two variable

    I have a formula for cost calculation that contain x and y two variable. I have to find the value of (x,y) where that formula will gives minimum value as cost should not be equal to zero, it has some minimum value. I took 1st partial derivative with respect to x and then with y and found the...
  6. A

    I Particle Creation function of beam energy

    This seems like it should be an easy and obvious thing to look up, but I had the hardest time finding it. Is there any graph which shows, as I increase the beam energy of a particle accelerator, what particles can be produced at each energy? Just looking for something ballpark here. Obviously...
  7. J

    Question about an Eqn. in Shankar - wave function probability

    I don't see why it is not ##P(\omega)\propto |\langle \psi | \mathbb{P}_{\omega}|\psi\rangle |^2.## After all, the wavefunction ends up collapsing from ##|\psi\rangle## to ##\mathbb{P}_{\omega}|\psi\rangle.##
  8. SchroedingersLion

    A Lennard Jones, 3 particles, partition function

    Greetings, similar to my previous thread (https://www.physicsforums.com/threads/lennard-jones-potential-and-the-average-distance-between-two-particles.990055/#post-6355442), I am trying to calculate the average inter-particle distance of particles that interact via Lennard Jones potentials...
  9. anemone

    MHB Integral of trigonometric function

    Prove that if $[a,\,b]\subset \left(0,\,\dfrac{\pi}{2}\right)$, $\displaystyle \int_a^b \sin x\,dx>\sqrt{b^2+1}-\sqrt{1^2+1}$.
  10. NTL2009

    Function of this piece in a loudspeaker?

    My son asked me to look at his Logitech Z-2300 system (Amp, sub-woofer and 2 satellite speakers) that was acting up. He had already taken a lot of it apart to see if he could find a loose connection. In checking things out, I found this part in with all the screws and loose hardware. It's the...
  11. K

    I Derivative of a function of another function

    This is really a simple question, but I'm stuck. Suppose we have a function ##\vartheta'(\vartheta) = \vartheta## and that ##\vartheta = \vartheta(\varphi)## and we know what ##\vartheta(\varphi)## is. How should I view ##\frac{\partial \vartheta'}{\partial \varphi}##? Should I set it equal to...
  12. Leo Liu

    Is the length of the arm r in a polar coordinate a function of the angle?

    My textbook says ##\vec r (\theta) = r \hat r (\theta)##, where ##\hat r (\theta)## is the terminal arm (a position vector in some sense). It can be seen that both ##\vec r (\theta)## and ##\hat r (\theta) ## are function of ##\theta##; whereas, the length of the vector ##r## is not. I...
  13. agnimusayoti

    Fourier series for trigonometric absolute value function

    First, I try to define the function in the figure above: ##V(t)=100\left[sin(120\{pi}\right]##. Then, I use the fact that absolute value function is an even function, so only Fourier series only contain cosine terms. In other words, ##b_n = 0## Next, I want to determine Fourier coefficient...
  14. S

    B Confusion about the domain of this logarithmic function

    Should I just follow the original question? If given as ##f(x)=\ln x^4## then the domain is x ∈ ℝ , x ≠ 0 and if given as ##f(x) = 4 \ln x## the domain is x > 0? So for the determination of domain I can not change the original question from ##\ln x^4## to ##4 \ln x## or vice versa? Thanks
  15. C

    MHB Implicit function theorem for f(x,y) = x^2+y^2-1

    $f: \mathbb{R^2} \rightarrow \mathbb{R}$, $f(x,y) = x^2+y^2-1$ $X:= f^{-1} (\{0\})=\{(x,y) \in \mathbb{R^2} | f(x,y)=0\}$ 1. Show that $f$ is continuous differentiable. 2. For which $(x,y) \in \mathbb{R^2}$ is the implicit function theorem usable to express $y$ under the condition $f(x,y)=0$...
  16. qbar

    A How Can I Differentiate Curves Where the Real Part of \( Y(t) \) Vanishes?

    Let $$Y(t)=tanh(ln(1+Z(t)^2))$$ where Z is the Hardy Z function; I'm trying to calculate the pedal coordinates of the curve defined by $$L = \{ (t (u), s (u)) : {Re} (Y (t (u) + i s (u)))_{} = 0 \}$$ and $$H = \{ (t (u), s (u)) : {Im} (Y (t (u) + i s (u)))_{} = 0 \}$$ , and for that I need to...
  17. wolfy

    B When the wave function collapses, how long is it collasped?

    When wave function collapses how long is it collasped... Shooting electrons at a double slit and observing the electrons before they reach the 2 slits collasped the wave function...so is its behavior particle like forever? Quantum mechanics is simple however wrapping ones head around it is...
  18. A

    A Identification of a probability density function

    I have the following probability density function: $$f(x) =...
  19. anemone

    MHB Finding $f(84)$ with the Defined Function $f$

    The function $f$ is defined on the set of integers and satisfies \[ f(n)=\begin{cases} n-3, & \text{if} \,\,n\geq 1000 \\ f(f(n+5)), & \text{if}\,\, n< 1000 \end{cases} \] Find $f(84)$.
  20. Kaguro

    Finding the potential function from the wavefunction

    I would differentiate this twice and plug it into the S.E, but for that I'll need E. Which I don't have. Please provide me some direction.
  21. M

    B Critical point of a piecewise function

    If the function is not differentiable at point. Can we consider this point is critical point to the function? f(x) = (x-3)^2 when x>0 = (x+3)^2 when x<0 he asked for critical points in the closed interval -2, 2
  22. Daniel Lima

    Python How to plot a function with multiple parameters on the same set of axes

    I attached a file with some explanations of the variables in the code and the plot that I should get. I don't know what is wrong. Any help will appreciated. from scipy.integrate import quad import numpy as np from scipy.special import gamma as gamma_function from scipy.constants import e...
  23. O

    MHB Evaluate some kind of gamma function

    My question and solution that I've tried out are in attachment. Is it true my steps?
  24. F

    Which sigma algebra is this function a measure of?

    Suppose ##\nu## is a measure on some ##\sigma##-algebra ##\mathcal{A}##. Then we must have for all ##A \in \mathcal{A}## either ##A## or ##A^c## is finite, but not both. Because otherwise ##\nu(A)## is undefined or not well defined. I've verified that ##\lbrace \emptyset, X \rbrace## and...
  25. S

    Laplace transform of an ODE with a non-smooth forcing function

    Suppose I'm solving $$y''(t) = x''(t)$$ where $$x(t)$$ is the ramp function. Then, by taking the Laplace transform of both sides, I need to know $x'(0)$ which is discontinuous. What is the appropriate technique to use here?
  26. agnimusayoti

    Indefinite integral of cross product of 2 function

    I've tried with this work in attachment. i&m not sure of my answer is correct.
  27. Terrycho

    I The wave function in the finite square well

    Hello! I have been recently studying Quantum mechanics alone and I've just got this question. If the potential function V(x) is an even function, then the time-independent wave function can always be taken to be either even or odd. However, I found one case that this theorem is not applied...
  28. peelgie

    Prove that this Function is a Homomorphism

    Summary:: Abstract algebra I have a problem with this task. Please help. [Moderator's note: Moved from a technical forum and thus no template.]
  29. P

    Plotting a Bessel Function for Diffraction (Fraunhofer)

    From my understanding of diffraction pattern is supposed to result in something like this However when I plot it I get the central peak without the ripples (even when broadening the view). My result My code is as follows %1) Define the grid. Define vectors so that they include 0...
  30. Y

    Objective function of a linear program with multiple variables

    Hello, Please I need help to find the objective function of a linear program (attachement : example). I tried to figure it out from the formula provided in (attachement : formula) but I couldn't understand it, it's written (MIN(lambda)wj) I think it's the key to my question ! ( Full file is...
  31. Eclair_de_XII

    Python Finding a local max/min of a function in Python

    Okay, so my algorithm looks something like this: ==== 1. Locate mid-point of the interval . This is our estimate of the local max. 2. Evaluate . 3. Divide the main interval into two subintervals: a left and right of equal length. 4. Check to see if there is a point in the interval such that ...
  32. G

    MHB How Can I Solve a Problem Using Euler's Totient Function for Odd Prime Numbers?

    Hello everyone, can anybody help me with this problem? The solution is for all odd prime numbers, but I have no idea how to solve it. Any help will be greatly appreciated.
  33. A

    A How to transform a probability density function?

    I have the following probability density function (in Maple notation): f (x) = (1 / ((3/2) * Pi)) * (sin (x)) ** 2 with support [0; 3 * Pi] Now I want to transform x so that 0 -> (3/2) * Pi and 3 * Pi -> (15/2) * Pi and the new function is still a probability density function. How should I...
  34. samuelfarley

    Calculus problem: Questions about the function f (x) = - x / (2x^2 + 1)

    shown in attachment
  35. leticia beira

    Finding the derivative of this trig function

    Para f (θ) = √3.cos² (θ) + sen (2θ), uma inclinação da reta tangente, uma função em θ = π / 6, é?
  36. jisbon

    Engineering Finding the transfer function for this circuit

    Transformed circuit: Using KVL, Now, I am unsure about the current to use KVL in this case. As far as equation goes: Vi(s) =(I1*R)+(I3*R)+Vc(s), where Vc(s) = V0(s)/u as shown in the circuit. How am I supposed to find the current I1 and I3 for the two resistors in this case? Thanks
  37. S

    Question about asymptotes of rational function

    I tried graphing the function in the calculator, and the graph seems to have a horizontal asymptote at y=0, not at y=1. Why is this so? Thanks for helping out.
  38. A

    A How to change the support of a probability density function?

    Given the support [a, b] of a probability density function. How can I change the formula for the probability density function with a support [u, v]? Example: Given the beta distribution with support [a=0,b=1]: $$\frac{x^{p-1} (1-x)^{q-1}}{Beta(p,q)}$$ Then the beta distribution with support...
  39. anemone

    MHB Evaluate the constant in polynomial function

    Let $a,\,b,\,c,\,d,\,e,\,f$ be real numbers such that the polynomial $P(x)=x^8-4x^7+7x^6+ax^5+bx^4+cx^3+dx^2+ex+f$ factorizes into eight linear factors $x-x_i$ with $x_i>0$ for $i=1,\,2,\,\cdots,\,8$. Determine all possible values of $f$.
  40. PGaccount

    I Partition function of quantum mechanics

    In quantum mechanics, we have the partition function Z[j] = e-W[j] = ∫ eiS+ jiOi. The propagator between two points 1 and 2 can be calculated as ## \frac{\delta}{\delta j_1}\frac{\delta}{\delta j_2} Z = \langle O_1 O_2 \rangle## The S in the path integral has been replaced by S → S + jiOi...
  41. Dwightun

    Maple How to get my function from these dsolve results

    Hi! I'm trying to solve ODE system with 2 equations Here is a result from dsolve. How can i get R(t) out of it And how to substitute initial conditions in it?
  42. BlueTempus

    ODE -> Transfer Function Assistance

    Homework Statement:: ODE -> Transfer Function Assistance Relevant Equations:: Newtonian physics, buoyancy, drag [Mentor Note -- thread moved to DE from the schoolwork forums, since it is for work and not schoolwork] Hello all, I'm new here but I'm looking for a bit of guidance with a...
  43. anemone

    MHB Can You Solve This Tricky Trigonometric Floor Function Equation?

    Solve $\{ \sin \lfloor x \rfloor \}+\{ \cos \lfloor x \rfloor \}=\{ \tan \lfloor x \rfloor \}$ for real solution(s).
  44. A

    MHB Question about Successor Function

    One of the Peano Axioms specifies Sa = Sb --> a = b where S is the successor function. How does one establish from the axioms that S is, in fact, a function, that is the converse a = b --> Sa = Sb? Probably a very simple matter, but I would appreciate any help in clarifying. Many thanks...
  45. A

    I Need help developing a movement function for motor motion

    Hi, I have a motor that i would like to rotate to a certain angle, in a controlled manner. During the movement, i want to update the final position I want to reach. The new updated function has to start with the same speed the initial function ended with I wan to find a function that does this...
  46. tworitdash

    A Integrating a function of which poles appear on the branch cut

    I have a complicated function to integrate from -\infty to \infty . I = \int_{-\infty}^{\infty}\frac{(2k^2 - \Omega^2)(I_0^2(\Omega) + I_2(\Omega)^2) - \Omega^2 I_0(\Omega) I_2(\Omega)}{\sqrt{k^2 - \Omega^2}} \Omega d\Omega Where I0I0 and I2I2 are functions containing Hankel functions as...
  47. S

    Engineering How does feedback affect the transfer function of an integrating block?

    The correct solution is different than my answer, I am not sure where I am going wrong?
  48. P

    Confirming Green's function for homogeneous Helmholtz equation (3D)

    Plugging in the supposed ##G## into the delta function equation ##\nabla^2 G = -\frac{1}{4 \pi} \frac{1}{r^2} \frac{\partial}{\partial r} \left(\frac{r^2 \left(ikr e^{ikr} - e^{ikr} \right)}{r^2} \right)## ##= -\frac{1}{4 \pi} \frac{1}{r^2} \left[ike^{ikr} - rk^2 e^{ikr} - ike^{ikr} \right]##...
  49. Adesh

    I Checking the integrability of a function using upper and lowers sums

    Hello and Good Afternoon! Today I need the help of respectable member of this forum on the topic of integrability. According to Mr. Michael Spivak: A function ##f## which is bounded on ##[a,b]## is integrable on ##[a,b]## if and only if $$ sup \{L (f,P) : \text{P belongs to the set of...
  50. chwala

    Find the sum of a function given a series

    since the first term is ##g(0)= \frac {1}{3}## & last term is ##g(1)=\frac {4}{6}## it follows that the ##\sum_{0}^1 g(x)##= ##\frac {1}{3}##+##\frac {4}{6}=1## is this correct?
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