Method Definition and 1000 Threads

  1. I

    MHB Estimate $y(0.5)$ using Euler's Method

    use euler's method with step size 0.1 to estimate y(0.5), where y(x) is the solution of the initial-value problem y'=y(x+1), y(0)=1. round your answer to four decimal places. this is all I've done so far $y'=y(x+1)$ $y(0)=1$ $h=0.1$ $x_{0}=0$ $y_{0}=1$ $x_{1}=x_{0}+h=0+0.1=0.1$...
  2. C

    Is It Possible to Use the Method of Undetermined Coefficients Here?

    I'm doing a practice problem I found online, and I get a solution, but I think it should have a sine term in it. I looked up the solution, and most sites say to use variation of parameters, but is it possible to use the method of undetermined coefficients? The problem is as follows: y'' + 4y...
  3. M

    Impact of trolley - hand calculation method

    Hello, Been a while since I posted on here, nice to be back :) . I just want some pointers as to the methodology for an impact load case that I'm looking at. I've attached a very basic sketch of a trolley which is traveling at a known velocity and impacts a rigid structure at it's base. What...
  4. E

    Why do we get oscillations in Euler's method of integration and what i

    When using Euler's method of integration, applied on a stochastic differential eq. : For example - given d/dt v=−γvΔt+sqrt(ϵ⋅Δt)Γ(t) we loop over v[n+1]=v[n]−γv[n]Δt+sqrt(ϵ⋅Δt)Γn. (where −γv[n] is a force term, can be any force and Γn is some gaussian distributed random variable. ) . Then if...
  5. D

    Converting MPa·mm1/2 to MPa.m1/2: A Scientific Approach

    I need to convert 12.5 MPa·mm1/2 into MPa.m1/2. I am unsure on how to do this, my two guesses are as follows: 1. (12.5) / ( 1 / 10001/2) = 395.28 MPa.m1/2 2. (12.5) / (12.5 / 10001/2) = 31.62 MPa.m1/2 Is either of those correct? Thanks!
  6. C

    MHB FE 1D method and hat functions

    Hi all, I'm doing a project on the finite elements method and am struggling to understand a part of it. I have defined the hat functions as: \[ \phi_i(x) = \begin{cases} \frac{x-x_{i-1}}{h} & \text{if } x_{i-1}\leq x<x_i \\ \frac{x_{i+1}-x}{h} & \text{if } x_i\leq x<x_{i+1}\\ 0 &...
  7. A

    Why Does Initial Approximation Affect Convergence Speed in Newton's Method?

    Homework Statement Use Newton's method with x1 = 1 to find the root of the equation x3 - x = 1 to correct six decimal places. Do the question again with x1 = 0.6 Do the question again with x1 = 0.57 You probably need to do it in an excel sheet. With each try, it takes longer to...
  8. H

    Structural Dynamics Analysis - Modal method or time integration?

    Hi all, I need help with numerical solution of motion equation. From the numerical point of view and in the real of the finite element method, which method is recommended for the solution of damped ( proportional damping) linear motion equation? I have been trying three common methods; Modal...
  9. R

    Iteration method for density equations

    hi there; I need some help with the following formulas In the interaction picture. ##\frac{d}{dt}\rho(t)=\frac{1}{i\hbar}[V(t),\rho(t)]## (1) Then ##\rho(t+\Delta t) = \rho(t)+\frac{1}{i\hbar}\int_t^{t+\Delta t} dt' [V(t'),\rho(t')]## (2) This equation can be iterated. and...
  10. T

    FE method, how ? (software Comsol)

    Hi all, The plastic flow rule for large strains in a continuum medium can be written as : -\dfrac{1}{2} \Big ( \dfrac{d}{dt}(F_p^{-1} ). ^t F_p^{-1} + F_p^{-1} . ^t \dfrac{d}{dt} ( F_p^{-1} ) \Big)= \lambda F^{-1} \dfrac{\partial f}{\partial \tau} F F_p^{-1} . ^t F_p^{-1} where F_p is the...
  11. R

    Programs Free online introductory classes good method of choosing an eng.major?

    I am an upcoming freshman. I will major in engineering. When applying to the school I chose mechanical because of its "versatility and stability in the job market." (I don't fully understand the meaning of these phrases; I get my knowledge from anecdotal experience when browsing forums). I may...
  12. W

    Newton-Raphson Method for Non-linear System of 3 variables in Matlab

    I am trying to solve 3 non-linear system of 3 variables using the Newton-raphson method in matlab. Here are the 3 non-linear equations: \begin{equation} c[\alpha I+ k_f+k_d+k_ns+k_p(1-q)]-I \alpha =0 \end{equation} \begin{equation} s[\lambda_b c P_C +\lambda_r (1-q)]- \lambda_b c P_C =0...
  13. A

    MHB Deriving potential energy by simulation method

    The picture shows the potential due to ring charge. Please show the full steps of deriving the equation of electrical potential. I don't know how to start at all. NOTE: The electric potential of the revolving symmetrical ring electric charge related to the axis z as depicted in the diagram...
  14. R

    MATLAB Newton-Raphson Method for Non-linear System of 3 variables in Matlab

    I am trying to solve 3 non-linear system of 3 variables using the Newton-raphson method in matlab. Here are the three equations: \begin{equation} c[\alpha I+ k_f+k_d+k_ns+k_p(1-q)]-I \alpha =0 \end{equation} \begin{equation} s[\lambda_b c P_C +\lambda_r (1-q)]- \lambda_b c P_C =0 \end{equation}...
  15. M

    MHB Method of characteristics-How can I continue?

    Hey! :o I have to solve the following hyperbolic system of equations using the method of characteristics: $$\left.\begin{matrix} \frac{\partial{u_1}}{\partial{t}}+\frac{\partial{u_1}}{\partial{x}}+x^2 \frac{\partial{u_2}}{\partial{x}}=0\\ \frac{\partial{u_2}}{\partial{t}}+t^2...
  16. S

    MHB How Do You Apply the Washer Method Correctly?

    Just doing the Washer Method for now, once that's sorted out I'm going to see if I can do the Shell Method. I just want to be sure I'm doing this right here. That's x=0, y=2, y=5-x This is around the X-Axis. R(y) = 5+y, r(y)=2 Assuming that part is at least correct. The integral goes from...
  17. S

    MHB Shell Method Example: Finding Volume Around Axes and a Line

    I don't need the answers or the problems worked out I'm asking something more basic. This is just an example problem. y=\sqrt(x),y=0, x=3 a) Around the x-axis R(x)=\sqrt{x}, r(x)=0 I understand the R to be the value fathers from the x-axis, and the r value to be the closer one to the...
  18. F

    Mesh (Loop Current) Method: tightening-up my recipe

    I'm an intro calc-based physics instructor, and recently uncovered some vagueness, or maybe errors (?), with my recipe. Can you please comment on the following? Question 1: Loop Currents - MY RECIPE: "Determine # of loop currents by connecting each circuit junction once, and only once, to a...
  19. T

    Weird shell method problem to find volume

    Y=x^(2/3) and y=x^2 rotated about the x=4. First I equate the equations giving me x=0,-1,1. The problem is I have exactly 2 graphs that are symmetric in respect to the y axis. N I have not encountered a problem in stewart dealing with this. I know that the volume on the right side of the...
  20. W

    How Can Newton-Raphson Method Solve These Complex Nonlinear Equations?

    The three non-linear equations are given by \begin{equation} c[(6.7 * 10^8) + (1.2 * 10^8)s+(1-q)(2.6*10^8)]-0.00114532=0 \end{equation} \begin{equation} s[2.001 *c + 835(1-q)]-2.001*c =0 \end{equation} \begin{equation} q[2.73 + (5.98*10^{10})c]-(5.98 *10^{10})c =0 \end{equation} Using...
  21. R

    MHB How to Solve Non-Linear Equations of 3 Variables Using Newton-Raphson Method?

    The three non-linear equations are given by \begin{equation} c[(6.7 * 10^8) + (1.2 * 10^8)s+(1-q)(2.6*10^8)]-0.00114532=0 \end{equation} \begin{equation} s[2.001 *c + 835(1-q)]-2.001*c =0 \end{equation} \begin{equation} q[2.73 + (5.98*10^{10})c]-(5.98 *10^{10})c =0 \end{equation} Using the...
  22. M

    Simplify Derivative of log(x^2 + y^2) - z^3

    Homework Statement Simplify ##d(log(x^2 + y^2) − z^3)## Homework Equations the derivative? The Attempt at a Solution The instruction says to simplify. In a similar problem I ended up using the d(a(b-c))= da d(b-c). I am not sure how to deal with the log and only found formulas...
  23. N

    The Lagrange Mesh Method: An Overview

    What is the Lagrange Mesh method?
  24. P

    Why is f(y,t+h) Equal to y(t+2) in Implicit Euler Method?

    Hey I don't understand this backward euler solution, in particular why the f(y,t+h) is equal to y(t+2)
  25. S

    MHB Finding an Expression for Y in a Linear Multistep Method

    consider the following LMM $$y_n-\frac{3}{2}y_{n-1}+\frac{1}{2}y_{n-2}=h(\frac{1}{2}f_n+\frac{1}{4}f_{n-1}-\frac{1}{4}f_{n-2})$$ which is applied to the initial value problem $$y'(t)=y(t),0\leq{t}\leq{1}\\ and\\ y(0)=1$$ How do i find an expression for $$y_n$$, if the starting values are...
  26. F

    Estimate Microbial Number: MPN Method for CFU

    Hi, I just want to know should I only use counts in tube3 to estimate microbial number, or the average of tube2 and tube3 estimation. Thank you!
  27. A

    The motivation of k.p method and envelope function method?

    There are various kinds of approximation methods in band theory. In my opinion, Bloch theorem implies the existence of energy band. From nearly-free electron approximation or tight binding method, we can calculate the energy band. They can tell us the information of band gap and band width...
  28. M

    Constructing Bending Moment Diagram for Member 1-5 Using Stiffness Matrix Method

    This problem has a lot of calculations from the beginning so i have skipped to the part i am stuck with and tried to include relevant information, apologies if i have missed anything. Assume all working is correct as i was given the answers. After carrying out the stiffness matrix method I am...
  29. P

    Example of the method of characteristics

    Homework Statement Hi,guys I have a example, i understand almost everything but i have problems understanding some steps. Example: 2u't+3u'x=0,x\inR,t>0,u(x,0)=sin(x),u=u(x,y) The Attempt at a Solution I rewrite the example (1)2u't+3u'x=u's (2)u'tt's+u'xx's=u's From comparing (1)...
  30. T

    Volume Measurement (Dry Method)

    Hi: I have been working in this Project for a while now and I would like to share the results with you. Still needs some improvements; but it appears to be working fine so far. Please let me know your suggestions and ideas. Thanks.
  31. Q

    Radius of the smallest exoplanet detectable with the transit method

    Please help me with this astronomy problem. I am supposed to calculate the smallest planet that is detectable with the transit method, given a signal to noise ratio and a star's radius: Suppose the star is seen at its distance D with a signal to noise ratio of S/N = 10^4. This means that in...
  32. N

    Bisection method and multiple roots

    Hello, I have a polynomial of order n and I want to find all it's roots with bisection method. Is it possible? I already wrote an algorithm to find a root and it's works nice for finding one of it's roots, but what about others? Nikola
  33. F

    2nd Order Differential Equation with Improved Euler Method (Heun's)

    Homework Statement I would like to solve a 2nd Order Differential Equation using the Improved Euler Method. The 2nd ODE is a Mass-Spring-Damper equation. I tried coming up with an solution for the Improved Euler Method, but not entirely sure. Can you help me and have a look if this is correct...
  34. J

    Karatsuba Method Homework: Check 3(r-1) Multiplications in F

    Homework Statement For polynomials f(x),g(x) of degree d = 2(r−1)−1, check that multiplying f(x) and g(x) by the Karatsuba method requires 3(r-1) multiplications in the field F. Homework Equations You can can more clearly see problem on page 383 #10...
  35. B

    MHB Do you have a diferent method to solve this Integral?

    Integral[(dx/(ex+1)] Here’s my method: If x = -Ln(u) Then dx = -du/u; ex = 1/u; u = e-x; Substituting in the integral we get: Integral[(-du/u)/((1/u)+1)] = -Integral[du/(1+u)] Solving the integer in terms of u: -Ln|1+u|+C Substituting x in the result: -Ln|1+e-x|+C Sorry that i didn't use the...
  36. W

    Asymptotic Expansion of Integrals Using Laplace's Method

    Consider the integral \begin{equation} I_n(x)=\int^{2}_{1} (log_{e}t) e^{-x(t-1)^{n}}dt \end{equation} Use Laplace's Method to show that \begin{equation} I_n(x) \sim \frac{1}{nx^\frac{2}{n}} \int^{\infty}_{0} \tau^{\frac{2-n}{n}} e^{-\tau} d\tau \end{equation} as x\rightarrow\infty...
  37. R

    MHB How Can Laplace's Method Simplify This Integral?

    Consider the integral \begin{equation} I_n(x)=\int^{2}_{1} (log_{e}t) e^{-x(t-1)^{n}}dt \end{equation} Use Laplace's Method to show that \begin{equation} I_n(x) \sim \frac{1}{nx^\frac{2}{n}} \int^{\infty}_{0} \tau^{\frac{2-n}{n}} e^{-\tau} d\tau \end{equation} as $x\rightarrow\infty$. where...
  38. R

    MHB Laplace's Method (Integration)

    Consider the integral \begin{equation} I(x)=\int^{2}_{0} (1+t) \exp\left(x\cos\left(\frac{\pi(t-1)}{2}\right)\right) dt \end{equation} Use Laplace's Method to show that \begin{equation} I(x) \sim \frac{4\sqrt{2}e^{x}}{\sqrt{\pi x}} \end{equation} as $x\rightarrow\infty$. => I have tried using...
  39. K

    How Do I Compute the Integral Using u-Substitution?

    what method should i use? i tried u = x - 4 du = dx i can't continue. enlighten me please
  40. W

    A predictor-corrector method and stability

    A predictor-corrector method for the approximate solution of y'=f(t,y) uses \begin{equation} y_{n+1}-y_{n}=hf_{n} \tag P \end{equation} as predictor and \begin{equation} y_{n+1}-y_{n}=\frac{h}{2}(f_{n+1}-f_{n}) \tag C \end{equation} IF (P) and (C) are used in PECE mode on the...
  41. T

    Rack and pinion, motor selection method

    Hi! I'm stuck on a very basic problem while trying to design a product. Basically, I need to know how to calculate the gear ratios, pitch, motor specs etc for two rack and pinion mechanisms- one horizontal and one vertical. The pinion moves along the rack in both situations. Mass to be moved-...
  42. D

    Hybrid Method for Solving linear equations

    Homework Statement What Hybrid Methods are used for solving linear equations and how are they advantageous to classic methods? Homework Equations The Attempt at a Solution Well I assume that more robust methods such as bisection would be combined with Newtons or secant which are...
  43. D

    Successive Substitution vs Newton's Method

    Homework Statement Name disadvantages of the Successive Method vs Newtons for solving nonlinear equations? Homework Equations The Attempt at a Solution I went all through the textbook and this is all I could find on the successive method disadvantages but these are not compared to...
  44. E

    MHB Solving Equivalent Expressions Using Subtraction Method

    How do you determine if the two expressions are equivalent using the subtraction method?$$\frac{2x^3+7x^2-5x-6}{x+1} - [(2x^2+5x-10) + \frac{4}{x+1}] $$ The textbook says that they're equivalent. I know that, using the subtraction method, they have to equal 0 in order to be equivalent. But, I'm...
  45. E

    A problem in sections method in analyzing structure

    Homework Statement Determine the force in members BF, BG, and AB, and state if the members are in tension or compression. Homework Equations Method of sections The Attempt at a Solution Now I cut the sections FB, BG and BA... I took the lower end. I now have three unknowns. I...
  46. I

    Simplex Method, Duality Problem

    Hello everyone, I have the following question: Show without using the simplex method that x1=5/26, x2=5/2, x3=27/26 is an optimal solution to the following LPP. Maximize z=9x1+14x2+7x3 subject to 2x1+x2+3x3<= 6 5x1+4x2+x3<= 12 12x2 <= 5 x1,x2,x3 unrestricted...
  47. R

    When determining if a decay is possible, is there a method to use?

    Hi, I'm in the process of revision for upcoming exams, one likely question will give a number of decays (~5) and ask if they are possible. I understand baryon number, lepton number (and parity, isospin, and strangeness) must be conserved, but for example for the following: K+ -> neutral...
  48. Q

    What would be the best method for heating copper tubing via nichrome?

    What would be the best method for heating copper tubing via nichrome wire? Voltage is 10
  49. E

    Four Wave mixing and split step Fourier method

    Hello everyone . I need to ask if I want to get the right units for each parameter to be able to get the right results Can anyone define them properly? Like the gamma the initial power of pump or signal dispersion and non linear factors Thank you
  50. PsychonautQQ

    Differential Equations Method of Undetermined Coefficients

    Homework Statement consider y'' + 2y' - 3y = 1 + xe^x, find the particular solution The Attempt at a Solution so f(x) = 1 + xe^x f'(x) =e^x + xe^x f''(x) = 2e^x + xe^x so it looks like my particular solution is going to have a constant term, an e^x term and an xe^x term, so I can...
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