Ode Definition and 1000 Threads

  1. AntSC

    Applying Boundary Conditions in Homogeneous ODE Problems

    Find the eigenvalues λ, and eigenfunctions u(x), associated with the following homogeneous ODE problem: {u}''\left ( x \right )+2{u}'\left ( x \right )+\lambda u\left ( x \right )=0\; ,\; \; u\left ( 0 \right )=u\left ( 1 \right )=0 Solution: Try u\left ( x \right )=Ae^{rx} , which gives...
  2. S

    Forward Euler Method for ODE system

    Homework Statement Solve the following system for 0<t<5 u^\prime = u-e^{-2t} v, u(0) = 1 v^\prime = u+3v, v(0) = -2 using Forward Euler method and implement the numerical scheme into a MATLAB code. Homework Equations Forward Euler : \vec x^(\prime)_{n+1} = \vec F(t,\vec x)...
  3. jimmy neutron

    Poincare's theorem and 2nd order ode

    This is a request about the second order differential equation y'' + (k^2 + f(r))y(r) = 0 (1) where k is a (real) constant and f(r) is a real valued function of r that has some constraints regarding integratability. According to...
  4. H

    MHB Assistance needed for this ODE problem

    Hi,The problem I am trying to solve is in a section on first order ODEs. It is problem 25 in section 2.1 of Boyce & DiPrima's Elementary Diff Eq (5th Ed). The problem serves as an introduction to the variation of parameters, but again, it is in the first section of the book that introduces first...
  5. G

    How can I draw a basic differential equation in Simulink?

    Homework Statement Hi, I was wondering if someone could help me create a basic differential equation in Simulink. I'm trying to create the following equations http://imageshack.com/a/img197/1379/cic.PNG I tried using this as an example...
  6. C

    MHB How to Solve This 2nd Order ODE in Control Systems?

    I'm trying to solve this equation analytically, but I can't even find the auxiliary equation or general solution! Km = 0.5 C*e = 0 K2 = 0.03 K1 = 0.05 x* = 49
  7. P

    What are the eigenfunctions for the ODE y′′−2xy′+2αy=0?

    Hi, Homework Statement I have the following ODE: y′′−2xy′+2αy=0 I'd like to determine the first three eigenfunctions. Homework Equations The Attempt at a Solution The solution y(x) may be recursively represented as: an+2=an(2n−2α)/[(n+2)(n+1)] I have found the eigenvalues to be...
  8. M

    Solving Logistic ODE with Non-commuting Matrices

    I'm trying to find a general solution for the logistic ODE \frac{dU}{dx}=A(I-U)U, where A and U are square matrices and x is a scalar parameter. Inspired by the scalar equivalent I guessed that U=(I+e^{-Ax})^{-1} is a valid solution; however, U=(I+e^{-Ax+B})^{-1} is not when U and A don't...
  9. A

    How to solve an ODE in the form y' = c + k*sin(y)

    I managed to stumble upon a differential equation such as the one above while doing some torque calculations and am wondering if and how to find the solution to it. I'm not that well versed in differential equations, so any help would be appreciated. Edit: A method to graph an integral line for...
  10. J

    Non-Homogeneous ODEs with Coupled Equations: Solving with Fourier Series?

    how do we solve an ODE which has forcing function in terms of Fourier series? i have attached a pdf file of the problem.
  11. MarkFL

    MHB Owen b's question at Yahoo Answers regarding a first order homogenous ODE

    Here is the question: I have posted a link there to this thread so the OP can view my work.
  12. MarkFL

    MHB Solve 2nd Order Linear Inhomogeneous ODE: Muhammad Fasih

    Here is the question: I have posted a link there to this thread so the OP may see my work.
  13. E

    Frobenius method for fourth order linear ODE

    By using frobenius method I find the roots of the indicial equation of a 4th order ODE to be 0, 1, 1, 2 Now, what is the form of the corresponding series solution of this equation with log terms?
  14. F

    Solving Initial Value ODE: x^2y''+xy'+y=0

    Homework Statement Solve the initial value problem: x^{2}{y}'' + x{y}' + y = 0, x>0, y(1)=1, {y}'=2 Homework Equations y=x^m The Attempt at a Solution x^{2}(m(m-1)x^{m-2})+xmx^{m-1} + x^{m} x^{2}(m(m-1)x^{m-2})+xmx^{m-1} + x^{m} x^{m}(m(m-1) + m + 1)...
  15. djh101

    Exploring the Finite and Infinite Solutions of ODEs with k < 1/4

    Consider \frac{d^{2}y}{dx^{2}}+\frac{k}{x^{2}}y = 0. Show that every nontrivial solution has an infinite number of positive zeroes if k > 1/4 and a finite number if k ≤ 1/4. Solving gives: y = Asin(\sqrt{k}ln(x)) + Bcos(\sqrt{k}ln(x)) And setting y = 0 gives: tan(\sqrt{k}ln(x)) =...
  16. N

    How to Derive the ODE for a Series RC Circuit with a Current Source?

    Dear all, I have problem to find the differential equation for my circuit shown in the attached picture. For input I have a current source, and the output is the voltage U (the voltage between the first and the ground node). I need the ODE to find the mathematical response of the system...
  17. MarkFL

    MHB Positive Roots of ODE Solution: K>1/4 has Infinite Zeros

    Here is the question: I have posted a link there to this thread so the OP can see my work.
  18. F

    Green's Function for Third Order ODE

    Homework Statement A dynamical system has a response, y(t), to a driving force, f(t), that satisfies a differential equation involving a third time derivative: \frac{d^{3}y}{dt^{3}} = f(t) Obtain the solution to the homogeneous equation, and use this to derive the causal Green's function...
  19. R

    Comp Sci Fortran programming to solve linear equation for ode

    Fint the exact solution of the system dy/dt = -15y-25z dz/dt=-47y-85z with inital condition y(0)=2, z(0)=5 either by writing the equation in matrix form as dx/dt =AX where x=(y z) and diagonalising the matrix A, or otherwise. Using fortran programming with second order adam bashforth...
  20. R

    Comp Sci Fortran programming for nonlinear ode

    Adapt the fortran programming using second order adams bashforth method to generate a numerical solution of the Lorenz system: dx/dt =-10x+10y dy/dy=28x-y-x*z dz/dt= x*y- (8/3)*z with initial condition x(0)=y(0)=0, z(0)=2 slightly perturbed. Plot x and z against t runs from 0 to 15, and also z...
  21. G

    Bessel's ODE: Why does taking ν≥0 matter? It is squared anyway.

    In Bessel's ODE x^{2}y''+xy''+(x^{2}-\nu^{2})y=0, why must \nu not be less than zero? I have looked it up, but I do not find a satisfying answer anywhere.
  22. O

    How difficult is it to solve this elliptic ODE.

    Hello, I am working on a research problem and I am not sure whether or not I will be able to figure this out in a suitable amount of time. I have never solved a single elliptic integral and they do seem non-trivial to gain an understanding of (most of the books I've glanced at assume a very...
  23. T

    Laplace Transform Solution to Second Order ODE IVP

    Homework Statement y''+6y=f(t), y(0)=0, y'(0)=-2 f(t)= t for 0≤t<1 and 0 for t≥1 Homework Equations The Attempt at a Solution L{y''}+6L{y}=L{t}-L{tμ(t-1)} where μ(t-1) is Unit Step Y(s)=L{y} sY(s)-y(0)=L{y'} and y(0)=0 s2Y(s)-sy(0)-y'(0)+6Y(s) where y(0)=0 and...
  24. C

    Power Series Solution to Linear ODE

    Homework Statement Let y(x)=\sumckxk (k=0 to ∞) be a power series solution of (x2-1)y''+x3y'+y=2x, y(0)=1, y'(0)=0 Note that x=0 is an ordinary point. Homework Equations y(x)=\sumckxk (k=0 to ∞) y'(x)=\sum(kckxk-1) (k=1 to ∞) y''(x)=\sum(k(k-1))ckxk-2 (k=2 to ∞) The Attempt at a Solution...
  25. O

    Solving the r(λ) Null Schwarzschild Geodesic: Methods and Challenges

    Homework Statement I am looking to solve the r(λ) null Schwarzschild geodesic in terms of the affine parameter λ, but I have not seen this done anywhere and I am not sure that it is even possible to do this somewhat close to analytically. As best I know there is no use-able boundary...
  26. M

    Solve ODE reducible to exact equation

    Homework Statement . Find all the solutions of the equation: ##\dfrac{\sin(y)}{x}dx+(\dfrac{y}{x}\cos(y)-\dfrac{\sin(y)}{y})dy=0## knowing that the equation admits an integrating factor ##u## of the form ##u(x,y)=h(\dfrac{x}{y})## The attempt at a solution. If I call...
  27. R

    Finding Recursion Relations for Coefficients in Power Series Solutions for ODEs

    Homework Statement I am trying to find the recursion relation for the coefficients of the series around x=0 for the ODE: y'''+x^2y'+xy=0 The Attempt at a Solution Therefore letting: y=\sum_{m=0}^\infty y_mx^m \therefore y'=\sum_{m=1}^\infty my_mx^{m-1} \therefore...
  28. C

    Second Order Linear ODE - Power Series Solution to IVP

    Homework Statement Let y(x)=\sumckxk (k=0 to ∞) be a power series solution of (x2-1)y''+x3y'+y=2x, y(0)=1, y'(0)=0 Note that x=0 is an ordinary point. Homework Equations y(x)=\sumckxk (k=0 to ∞) y'(x)=\sum(kckxk-1) (k=1 to ∞) y''(x)=\sum(k(k-1))ckxk-2 (k=2 to ∞) The Attempt at a Solution...
  29. N

    General Solution of 2y'+y-(2y')*ln(y')=0

    Homework Statement Find the general solution of 2y' + y - (2y')*ln(y') = 0 Homework Equations The Attempt at a Solution I have no idea how to deal with this i mean none of the first order techniques work and it's mainly because I don't know how to deal with the ln(y'). I tried seperating...
  30. L

    Solving simultaneous equation for an ODE BVP.

    Homework Statement Hello, We are getting a quick taste of Boundary Value Problems in my ODE class and the application is deflection of beams. Basically I get to the point where I need to solve for the constants, but each constant appears in each equation but the powers of L are throwing me...
  31. M

    Help connecting vector fields in ODE and Vector Calc

    The vector field F=<y,x> looks exactly like the the direction field for the system dY/dt = {dx/dt = y} {dy/dt = x} A few questions on this: Are the direction field of a system of ODE's the same as a vector field of calculus? In vector calc we take the line integral of a vector field...
  32. A

    Which Class Should I Take: Upper Division ODE or PDE?

    I'm trying to decide between taking an ODE class or a PDE class next. I have already done Calculus 1,2,3 so I already know some ODEs and PDEs and linear algebra. I'm a 3rd year mathematics major with a minor in Statistics and I'm interested in applied mathematics.ODE course coverage: Ordinary...
  33. A

    MATLAB Critical points of system of ODE in MATLAB - Game theory and poker

    Hello there, I hope I'm posting in the right section. I have been doing some work on evolutionary game theory and poker. I will give a brief description of how I got here. I have eight strategies i = 1, 2, \ldots, 8 and the eight proportions of the population playing each strategy is...
  34. C

    MHB Why Do Solutions to This ODE Differ?

    \[y'sin(x)= yln(y)\] Hi, I am trying to solve this one but i can't find the same result of the book: Here is my solution:
  35. J

    MHB How to Solve This ODE with Substitution?

    I haven't done ODEs in a while nor have a book handing. How do I tackle an equation of the form \[ 2xyy'=-x^2-y^2 \] I tried polar but that didn't seem to work.
  36. D

    Nonseparable ODE which method to use

    Homework Statement $$ \left(\frac{du}{dx}\right)^2 = au^2 + bu + c $$ Homework Equations The Attempt at a Solution What method is used to solve and ODE of this form
  37. MarkFL

    MHB Solve 2nd Order Inhomogeneous ODE: Kartika's Q on Yahoo Answers

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  38. F

    MHB Getting wrong answer to differential equation (first order separable ODE)

    \sqrt{1-y^2}dx - \sqrt{1-x^2}dy=0, y(0)=\frac{\sqrt{3}}{2} rewriting the equation gives \frac{1}{\sqrt{1-x^2}}dx = \frac{1}{\sqrt{1-y^2}}dy Isn't this the integral for \sin^{-1}(x) & \sin^{-1}(y)? The back of book has y=1/2x+\frac{\sqrt{3}}{2}\sqrt{1-x^2}
  39. alane1994

    MHB Solve 4th Order Linear ODE and Plot Graph: t→∞

    Find the solution of the given initial value problem, and plot its graph. How does the solution behave as \(t\rightarrow\infty\) \(y^{(4)}-4y'''+4y''=0\) My work, which coincidentally I believe is incorrect... From the above differential equation, \(r^4-4r^3+4r^2=0\) \(r^2(r-2)^2=0\)...
  40. MarkFL

    MHB Find a Particular Solution y_p for 2nd Order ODE at Yahoo Answers

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  41. Y

    Second order nonhomogeneous ODE

    Homework Statement y''+3y'+3.25=3cost-1.5sintHomework Equations yh = e(a/2)t(Acost+Bsint) yp = Kcos(ωt)+Msin(ωt) [when r(x)=kcos(ωt) or ksin(ωt)]The Attempt at a Solution I got the homogeneous solution, which is e-1.5t(Acost+Bsint) but I am having trouble with the particular solution. I...
  42. djh101

    Solving ODE Oscillations: Find T for Buoy & Train Round Trip

    1. A spherical buoy of radius r floats half-submerged in water. If it is depressed slightly, a restoring force equal to the weight of the displaced water presses it upward; and if it is then released, it will bob up and down. Find the period of oscillation if the friction of the water is...
  43. skate_nerd

    MHB ODE for a forced, undamped oscillator.

    I have a physics problem right now, and I am so close to finishing it... The problem is to consider an undamped (no friction) forced mass-spring system. The forcing is given by $$F(t)=F_o\cos{\omega_ft}$$ The general ODE for this would be $$\ddot{x}+(0)\dot{x}+\omega_o^2x=f_o\cos{\omega_ft}$$...
  44. B

    Method of Frobenius for Solving ODE at x=0 | Step-by-Step Guide

    Homework Statement Using method of frobenius about x=0 to solve: (1-x) y''+xy'-\frac{\alpha^2}{x^2}+=0 Homework Equations N/A The Attempt at a Solution 1. plug in series into the equation. 2. adjust the index off all the terms. 3. write the extra terms separately so that we have...
  45. MarkFL

    MHB MCK's questions at Yahoo Answers regarding an inexact ODE

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  46. shinnsohai

    How Can the Superposition Principle Help Solve an ODE with Initial Conditions?

    Homework Statement Given \frac{dx}{dt} = -1.3x x_{1}(t)=e^{-1.3t} x_{2}(t)=4e^{-1.3t} Compute a solution for x(t) if x(0)=3 Homework Equations Superposition Principle and some ODE related Anyhow I refer to this http://www.youtube.com/watch?v=_ECd0Jn7y68The Attempt at a Solution First...
  47. MarkFL

    MHB Solving Point of Tangency for AP Calculus BC Problem

    Here is the question: I have posted a link there to this topic so the OP can see my work.
  48. H

    How Do You Solve for Position x(t) Given a Force Dependent on Velocity?

    A particle of mass m is subject to a force F(v) = bv^2. The initial position is zero, and the initial speed is vi find x(t) so far m*dv/dx*v = -bv^2 m*dv/dx = -bv integral m/-bv*dv = integral dx m/-b*ln(v) + a = x + b What do I do with the constants? i thought i was suppose to put...
  49. GreenAce92

    Can I split up the left hand side of an ODE?

    Should I just assume that any problems that involve integrating factor will always result in a perfect integral pair? That's probably not the right terminology but for instance if I have a differential equation which has had an integrating factor multiplied to both sides, then the left hand side...
  50. J

    Solving ODE for $\sigma$: Transformation and Manipulation?

    Hi all, I have an ODE of the form \frac{d^{3}\psi}{d\xi^{3}}-A\left(\psi+\xi\frac{d\psi}{d\xi}\right)=0, where \psi=C_{1}U(\xi)+C_{2}V(\xi). Is there any transformation or inventive manipulation I can use here to obtain an ODE for \sigma=U(\xi)+V(\xi)? As this is the quantity I would...
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