Method Definition and 1000 Threads

  1. M

    MHB Method of least square: initial position & velocity

    Hey! :o A point is moving linearly with constant velocity $v$ and the movement is $x=a+vt$. The below information is given: Find the initial position $a$ and the velocity using the method of least square. Could you give me a hint how we use this method here? Couldn't we use the data of...
  2. P

    Programming a Diffraction Pattern by the (pseudo?) method of images

    I oriented a magnetic dipole perpendicular to the hole (parallel to the ŷ ŷ y^ŷ direction) with one end at it's origin and I get the following pattern I was really looking for something like this As you can see I'm getting almost the exact opposite of what I want since I'm going for...
  3. M

    MHB Determine the position using an iteration method

    Hey! :o The function \begin{equation*}f(x)=\frac{x}{e^{x/9}}\cdot \frac{\sin \left (\pi (x-1)\right )}{x-1}\end{equation*} has at exactly one position $\overline{x}>1$ the same value as at the position $x=1$. Determine the position $\overline{x}$ using an iteration method with accuracy of two...
  4. P

    MHB Lachlan's question via email about the Bisection Method

    The Bisection Method solves equations of the form $\displaystyle f\left( x \right) = 0 $ so we must write the equation as $\displaystyle 11\cos{ \left( x \right) } - 1 + 2\,\mathrm{e}^{-x/10} = 0 $. We can then see that $\displaystyle f\left( x \right) = 11\cos{ \left( x \right) } - 1 +...
  5. P

    MHB Hayldiburasomas' question via email about Secant Method

    The Secant Method is a numerical scheme to solve equations of the form $\displaystyle f\left( x \right) = 0 $, so we must rewrite the equation as $\displaystyle 0 = \frac{1}{2}\,x^2 - 10 - \sin{ \left( 1.8\,x \right) } $. Thus $\displaystyle f\left( x \right) = \frac{1}{2}\,x^2 - 10 - \sin{...
  6. P

    MHB Alexander's question via email about Newton's Method

    Alexander asks: Apply three iterations of Newton's Method to find an approximate solution of the equation $\displaystyle \mathrm{e}^{1.2\,x} = 1.5 + 2.5\cos^2{\left( x \right) } $ if your initial estimate is $\displaystyle x_0 = 1 $. What solution do you get?
  7. P

    MHB Lachlan's question via email about the Bisection Method

    The Bisection Method is used to solve equations of the form $\displaystyle f\left( x \right) = 0 $, so we need to rewrite the equation as $\displaystyle 8\cos{ \left( x \right) } - \mathrm{e}^{-x/7} = 0 $. Thus $\displaystyle f\left( x \right) = 8\cos{ \left( x \right) } - \mathrm{e}^{-x/7} $...
  8. Leonardo Machado

    A Rational Chebyshev Collocation Method For Damped Harmonic Oscilator

    Hello everyone. I'm currently trying to solve the damped harmonic oscillator with a pseudospectral method using a Rational Chebyshev basis $$ \frac{d^2x}{dt^2}+3\frac{dx}{dt}+x=0, \\ x(t)=\sum_{n=0}^N TL_n(t), \\ x(0)=3, \\ \frac{dx}{dt}=0. $$ I'm using for reference the book "Chebyshev and...
  9. J

    MHB Minimum Degree of a Random Graph (Probabilistic Method)

    Problem: Suppose that the function $p : N \rightarrow [0, 1]$ satisfies $p >> n^{-1}ln(n)$ (i.e. $n^{-1}ln(n) = o(p)$). (a) Prove that as $n \rightarrow \infty$, the random graph $G(n, p)$ has minimum degree at least $\frac{np}{2}$ almost surely. Idea: Look at the degree of each individual...
  10. bagasme

    B Derivation of Cosine and Sine Method of Vector Sum

    Hello all, In high school physics, the magnitude sum of vector addition can be found by cosine rule: $$\vec {R^2} = \vec {F^2_1} + \vec {F^2_2} + 2 \cdot \vec F_1 \cdot \vec F_2 \cdot cos ~ \alpha$$ and its angle are calculated by sine rule: $$\frac {\vec R} {sin ~ \alpha} = \frac {\vec F_1}...
  11. Eclair_de_XII

    B Is this method of estimating Pi too similar to Archimedes' method?

    The recurrence relation was given as: ##p_k=2^{k+1}\cdot h_k## where ##h_0^2=2## ##h_{k+1}^2=(\frac{1}{2}h_k)^2+(1-\frac{1}{2}h_k \cdot \cot(2^{-k}\cdot \alpha))^2## and ##\alpha=\arctan(1)##. This is not exactly an original or noteworthy derivation, is it? I feel that it's been done...
  12. R

    Misc. Mechanism or method to unlock a window from the outside?

    Hello, I hope this is the right place to post about this. I live in a multi-unit condo, and I have a window that I am trying to lock and unlock from the outside. The window is from the kitchen and looks out onto a public-ish breezeway where I can access easily. I know this might seem a...
  13. L

    Finite difference method for the diffusion-advection equation

    So for my scheme I obtained ##\frac{\mu}{h^2} U_{p}+(\frac{v_{1}}{2 h}-\frac{\mu}{h^2})U_{E}+(\frac{v_{2}}{2 h} - \frac{\mu}{h^2})U_{N} - (\frac{v_{1}}{2 h}+\frac{\mu}{h^2})U_{W} - (\frac{v_{2}}{2 h} + \frac{\mu}{h^2})U_{N} + \tau = f## however I am not sure this is correct. I am quite new to...
  14. V

    Python Is My Python Bisection Method Code Correct?

    import math def poly(x): return (x**4 + 2*x**3 - 7*x**2 - 8*x + 12) def bisect(f,a,b,tol=1e-6): while (b-a)>tol: m=(a+b)/2 if (f(a)>=0>=f(m)) or (f(a)<=0<=f(m)): b=m else: a=m return (f(a),a) print(bisect(poly,-4,-2.5)) Here is...
  15. H

    I The irreducible representations of of su(2): Highest weight method

    Hi all I need to understand the following passage from Hall link page 78 : Some notation first: Basis for ##sl(2;C)##: ##H=\begin{pmatrix} 1&0\\0&−1\end{pmatrix} ;X=\begin{pmatrix} 0&1\\0&0\end{pmatrix} ;Y=\begin{pmatrix} 0&0\\1&0\end{pmatrix} ## which have the commutation relations...
  16. T

    Quick Method of Calculating the 2nd Moment Of Area Of an I Beam

    Hi All I was wondering if there was a quick method of calculating the Second Moment Of Area about the Z axis shown below? I can quickly work out the Second Moment Of Area about the Y axis but the Z axis is proving very difficult and time consuming as the parallel axis therom needs to be...
  17. M

    Stiffness Matrix Method: Symmetry vs Introducing a new node / joint

    Hi, In the question outlined in the images (apologies for the poor quality of the scans), the chosen solution has opted to use a symmetry argument and proceed from there. Question is from "Structures: theory and analysis" by Williams & Todd My question is: How could we approach the same...
  18. T

    Abuse of the Finite Element Method

    In general, one could say the Finite Element Method is merely an interpolation method that could be used to solve field equations. Despite that, this question focuses exclusively on the FE Method and its use in Mechanical Engineering. ------------------- I have noticed that some schools now...
  19. C

    Trapezoid method converges faster than the Simpson method

    Good Morning, I have been doing computer practices in C ++, and for an integration practice, the trapezoid method converges faster than the Simpson method. The function to be integrated is a first class elliptical integral of the form: Where k is bounded between [0,1). I have been thinking...
  20. C

    Doubts about the method of determining the elastic constant of a spring

    Good afternoon,I am preparing a laboratory report on the study of the oscillations of a spring and the following questions have arisen:The script asks us to represent the mass against the squared period, in this case, the slope will correspond to the spring constant divided by 4Π^2 and the...
  21. C

    I Does the Euler method give a better insight into adiabatic processess?

    I verified with others the equation below is an Euler method as well with ##a## can be any value such that it give the same ##\frac{dE}{dv}=-1.4\frac{p}{v}## but with ##a## other than one, it have no meaning in physics. For anyone that already understand Euler method can omit the part i have...
  22. E

    Not sure why my method doesn't work: Springs, Potential Energy and Work

    I know that you can get the answer through using Fs as 18 and solving for K, then subbing it into the equation for elastic energy. I was just wondering why another method wouldn't work. I tried doing it using the concept that Work is an equal to the Change in Elastic Energy, therefore Ee=xF...
  23. JD_PM

    Understanding how to apply the method of images to the wave equation

    Exercise statement Find the general solution for the wave equation ftt=v2fzzftt=v2fzz in the straight open magnetic field tube. Assume that the bottom boundary condition is fixed: there is no perturbation of the magnetic field at or below the photosphere. Solve means deriving the d’Alembert...
  24. A

    I Constants at the end of the Frobenius method

    I'm having a hard time grasping the concept of reducing the two recursive relations at the end of the frobenius method. For example, 2xy''+y'+y=0 after going through all the math i get y1(x) = C1[1-x+1/6*x^2-1/90*x^3+...] y2(x) = C2x^1/2[1-1/3*x+1/30*x^2-1/630*x^3+...] I know those are right...
  25. J

    B Understanding Horner's Method: A Brief Explanation for Confusion

    So I was trying to understand Horner's method. I understand that you can take a polynomial and factor out the x's and re write it as multiple linear functions recursively plugged into each other and that this makes evaluating a polynomial easier because you just evaluate a linear function...
  26. Purahei

    Fortran Discrete Element Method in FORTRAN 90 for collisions of particles

    Does anyone know a simple implementation in FORTRAN 90 of collisions of particles?
  27. C

    Doubt about Jacobi's diagonalization method

    Good Morning, I am using the Jacobi diagonalization method for symmetric matrices and I have realized that as the number of iterations progresses, the speed with which the larger element (in absolute value) outside the diagonal of the diagonal becomes smaller Matrices are increasing (graphical...
  28. ExplosivePete

    I Using the Variational Method to get higher sates

    In a typical quantum course we learn how to approximate the ground state of a particular Hamiltonian by making an educated guess at an ansatz with a tunable parameter then calculating the expectation energy for the ansatz. The result will depend on the tunable parameter if done correctly. Then...
  29. B

    WKB method transmission coefficient

    Homework Statement: The Task is to calculate the Transmission coefficient with the WKB Approximation of following potential: V(x) = V_0(1-(x/a)²) |x|<a ; V(x) = 0 otherwise Homework Equations: ln|T|² = -2 ∫ p(x) dx I have inserted the potential in the equation for p(x) and recieved p(x) =...
  30. T

    What do the numbers in the method of joints analysis for trusses represent?

    Hello all I am trying to analyse a truss using the method of joint process i.e I am trying to determine whether each member is in tension or compression. I have the following truss that I want to analyse using the method of sections. Just focusing on joint A, I have created a FDB and...
  31. jisbon

    Calculating Newton's Method: Step-by-Step Guide

    Since the Newton's method is as follows: $$x_{n+1}=x_{n}-\frac{f(x_{n})}{f'(x_{n})}$$ $$x_{1}=x_{0}-\frac{cos(0)-1}{-sin(0)-2}$$ Is this correct? What should I proceed on from here?
  32. N

    How to judge the singularity of a matrix in numerical method?

    Summary: different methods give different results. They are not consistent. Summary: different methods give different results. They are not consistent. I use two different methods to detect whether a matrix is singular. The result of calculating the determinant of a 9-order square matrix is...
  33. R

    Experimental method question - electrochemistry

    I am looking at a paper (ref below) that uses a method to precipitate calcium carbonate on a steel pipe. However, the paper gives no method because the reference it uses is linked to a thesis that has not been released. The setup is below... Now, I kind of understand that it uses a method of...
  34. H

    A Crank-Nicholson method and Robin boundary conditions

    I have the following PDE I wish to solve: \frac{\partial u}{\partial t}=D\frac{\partial^{2}u}{\partial x^{2}} With the following boundary conditions: \frac{\partial u}{\partial x}(t,1)+u(t,1)=f(t),\quad u(t,0)=0 Now, I wish to do this via the Crank-Nicholson method and I would naively...
  35. karush

    MHB 2.2.294 Euler's method word problem

    George makes a paper boat with his brother Bill and goes out in the rain to play with it. It falls in the stream along the curb, racing towards the sewer. Let t be measured in seconds, p be the velocity of the paper boat in meters/second and g be George’s velocity, measured in meters/seconds...
  36. karush

    MHB How Accurate is Euler's Method for Solving Differential Equations?

    Use Euler's method to approximate the value of y at $x=1$ on the solution curve to the differintial equation $$\dfrac{dy}{dx}=x^3-y^3$$ that passes through $(0,0)$, Use $\Delta x = \dfrac{1}{5}$ or 5 steps $\quad x_{1}=x_{0}+h=0+\frac{1}{5}=\frac{1}{5}$ $y\left(x_{1}\right)=y\left( \frac{1}{5}...
  37. Huyanyinglei

    A Need help understanding Lambda Twist method for camera localization?

    I have the following problem. P-n-p problem is often referred to when talking about camera localization(https://en.wikipedia.org/wiki/Perspective-n-Point). It’s a mathematical problem also a computer science problem. Lambda Twist is one of the state-of-the-art...
  38. Another

    What is the Savitzky-Golay 2nd derivative method?

    How are Savitzky–Golay second derivative different from Savitzky–Golay smoothing?
  39. Arman777

    Comp Sci Solving 2nd Order DEs with 4th Order RK Method

    In second order case we should rewrite the equation in terms of 2 first order DE's. So I wrote, $$dx/dt = wx$$ $$dwx/dt = -GMx/r^3$$ and $$dy/dt = wy$$, $$dwy/dt = -GMy/r^3$$ Now I guess there's two ways to do it in 4th order RK method. I would either do it component by component or just in...
  40. S

    [E&M] Question on the Image charge method of a grounding sphere

    So I was reading Jackson's discussion on Image charge method of a grounding sphere. He first assumed an image charge q inside Sphere with radius a, so the potential for real change and image charge is . The by set potential equal to 0 at x=a, he solved q' and y' Then he can get potential...
  41. sdefresco

    3-D Planar Method of Images Boundary Problem

    I understand the idea of the method of images, and its clever use of uniqueness to determine V(x,y,z) for non-trivial systems. My question now is simply about guidance for obtaining the effective "image" of this system, as it is clearly more complicated than the 2-plane analogue (in which there...
  42. S

    Lill's method for solving polynomial equations

    Summary: Worth teaching in secondary school? - or too bewildering? The mathologer video made me aware of Lill's method for solving polynomials with real roots. Although I'm not involved in secondary school teaching, I can't help wondering if it is a suitable topic for that level. Perhaps...
  43. e101101

    Energy Method: Inclined Plane - Solving for Velocity and Time

    So far I've got E=1/2m(dx/dt)^2+mgh this can be rewritten as (dx/dt)^2=2(E-mgxsin(Θ))/m Would there not be a positive and negative solution? dx/dt=±sqrt(2(E-mgxsin(Θ))/m) or do we discard the negative one? Why would we do so, if that's the case. So far I've only solved the postive solution and...
  44. G

    Any plausible non-rocket based method to reach orbit?

    Recently i read, that GEO orbit actually isn't enough for a space elevator, since its weight would pull it down, either it needs constant thrust, or build it much taller than 33.000 km, so upper GEO parts pull it up. That further lowers its plausibility level. Any other methods? Build a tall...
  45. X

    Cube root long division method

    On the right paragraph it says "The trial divisor 1200 goes into the dividend 13952, 8 times" Clearly 1200 goes into 13952, 11 times. I don't understand why 8 is (arbitrarily?) chosen. Please help. Thanks.
  46. X

    I Challenges to the Redshift Method and Hubble's Law

    Since Hubble's Law has been around a long time, so, after almost 100 years, to challenge its validity looks like dumb and stupid. So let me be that dumb guy, or maybe the bad boy that spoils the whole thing. Here let me start with the Redshift in general. There are three Redshifts proposed till...
  47. TytoAlba95

    Which method is best for GCL assay and Why?

    I'm trying to choose a protocol for estimating GLutamate Cysteine ligase assay. I've two of them. Reaction: L-glutamate + L-cysteine + ATP gamma-glutamyl cysteine + ADP + Pi #Protocol 1: Dasgupta 2007 Though this method, the author has estimated GCL activity by measuring a blue coloured...
  48. D

    I What Is the Best Numerical Method for Solving a PDE on a 2D Annulus Grid?

    I am attempting to solve the following PDE for Ψ representing a stream function on a 2D annulus grid: (1/s)⋅(∂/∂s)[(s/ρ)(∂ψ/∂s)] + (1/s2)⋅(∂/∂Φ)[(1/ρ)(∂ψ/∂Φ)] - 2Ω + ρ(c0 + c1ψ) = 0 I have made a vertex centered discretization: (1/sj)⋅(1/Δs2)⋅[(sj+1/2/ρj+1/2,l){ψj+1,l - ψj,l} -...
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