# Differential Equations

- An equation involving derivatives of a function or functions. Solving ODE and PDE
 Meta Thread / Thread Starter Last Post Replies Views Please post any and all homework or other textbook-style problems in one of the Homework & Coursework Questions... Feb23-13 10:24 AM micromass 1 24,584 Pinned: Intro. to Differential Equations ( 1 2 3 ... Last) My intent is to create a thread for people interested in Differential Equations. However, I will explicitly state that... Jul3-12 08:18 PM Luccas 95 117,358 1) If u(r,\theta,\phi)=\frac{1}{r}, is \frac{\partial{u}}{\partial {\theta}}=\frac{\partial{u}}{\partial {\phi}}=0... Y 09:25 PM jasonRF 4 109 Dear all, I have problem to find the differential equation for my circuit shown in the attached picture. For... Y 03:06 AM ntmkd 2 179 I've been trying to solve the Romeo and Juliet problem in differential equations: Romeo is in love with Juliet, but... Dec10-13 11:21 PM ckelly94 9 1,399 Find a topological conjugation between g(x) and T(x) where g and T are mappings (both tent maps ) g: → g(x) =... Dec10-13 03:31 PM selig5560 0 126 For spherical coordinates, u(r,\theta,\phi) is function of r,\theta,\phi. a is constant and is the radius of the... Dec10-13 01:57 AM fzero 1 150 Want to understand a concept here about dimensions of a function. Using example 1: a simple fourier series from... Dec9-13 02:39 PM HallsofIvy 1 230 Here is the DE: Δu(r,θ)=0, 1 ≤ r ≤ 2, 0 ≤ θ ≤ pi and here are the Boundary Conditions: u(1,θ)=sin(θ), u(2,θ)=0,... Dec9-13 11:22 AM pasmith 1 188 Hello,I have a problem in writing my code in Mathematica, when I put values of R,T,S&a the system worked and gave me... Dec7-13 07:33 PM Bill Simpson 4 303 \frac{\partial{u}}{\partial{t}}=\frac{\partial^2{u}}{\partial{r}^2}+ \frac {2}{r} \frac... Dec5-13 09:14 PM jasonRF 13 414 Dear All, I have following first order nonlinear ordinary differential and i was wondering if you can suggest some... Dec5-13 06:44 AM epenguin 5 722 Hi everybody, I'd like to solve the following "free boundary PDE" numerically. Does anybody knows about some... Dec4-13 04:35 AM re444 0 209 I have two questions: (1)As the tittle, if u(a,\theta,t)=0, is \frac{\partial{u}}{\partial... Dec3-13 02:44 PM yungman 5 271 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... Dec3-13 01:28 AM yungman 5 300 Hello Guys. I have to solve two coupled PDE coming from a quantum physical problem, which possess a cylindrical... Dec1-13 07:45 AM Physteo 0 226 Hello, Background: I was going to implement an implicit approach to 3d tetrahedra deformations (first in Matlab... Nov30-13 05:09 PM datahead8888 0 290 Consider the ODE x(x-1)y''-xy'+y=0. I need help in identifying the method of solution (power series or frobenius)... Nov30-13 05:01 AM JJacquelin 1 283 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... Nov30-13 04:39 AM JJacquelin 2 318 How to solve this differential equation \left(\frac{dy}{dx}\right)^{4}+B\left(\frac{dy}{dx}\right)^{3}+C=0 ... Nov29-13 05:38 PM Simon Bridge 1 339 What is the answer of this differential equation. ((d^2) r)/((ds)^2) +(m/(r^2)) -(nr/3)=0 the boundary... Nov29-13 03:14 PM kumudumalee 2 258 I have not met differential equations involving the composition functions (also not much literature on it). Assume... Nov28-13 12:17 PM dftfunctional 5 365 Consider the ODE y''+P(x)y'+Q(x)y=0. If \stackrel{limit}{_{x→x_{o}}}P(x) and \stackrel{limit}{_{x→x_{o}}}Q(x)... Nov27-13 03:47 AM gikiian 2 350 Hello, We were introduced to Laplace transforms in my ODE class a few days ago, so naturally I went online to try... Nov26-13 01:08 PM AlephZero 2 382 I was working on PDE for a project and needed to compute a Jacobian for it. Suppose we have a function consisting... Nov24-13 02:19 PM datahead8888 0 457 We first express Bessel's Equation in Sturm-Liouville form through a substitution: ... Nov24-13 11:39 AM pasmith 2 386 I am working on a motorcycle dynamics problem. I have written the equations of motion in matrix form in matlab (and... Nov22-13 07:43 PM AlephZero 7 502 First a little warm up problem. Suppose g:\mathbb{R}^N\to\mathbb{C} is some fixed function, and we want to find... Nov21-13 06:41 PM jostpuur 2 444 Helmholtz equation stated that \nabla^2 u(r,\theta,\phi) =-ku(r,\theta,\phi) = f(r,\theta,\phi) This is being used... Nov21-13 03:12 PM yungman 0 430 Hi everybody, I need to solve a 1st order PDE for my thesis and I'm not a specialist in this field. I've read some... Nov20-13 07:36 PM Chestermiller 5 497 I have the following differential equation which I want to solve for y as a function of x ... Nov19-13 07:51 AM PSarkar 3 519 I am currently taking a course in PDE's and it has been very "applied" and not so much theory based. I can say its... Nov18-13 11:14 AM DeIdeal 4 494 Hello everybody, I have a small question related to multigrid. I am trying to solve a Poisson equation in 3D with... Nov18-13 06:04 AM kolmog 0 348 hey pf! here's the question: $$u \frac{ \partial u}{ \partial x} = \rho \frac{ d P}{ d x}$$ may i generally state... Nov18-13 02:45 AM joshmccraney 2 370 If a_3(x)y'''+a_2(x) y''+a_1(x) y'+a_0(x)y=f(x) is an ODE with particular solution y_{p1} and a_3(x)y'''+a_2(x)... Nov18-13 01:03 AM gikiian 4 487 How do I find the second derivative of the function: f(x)= x^(2/3) (6-x)^(1/3) I have found the first... Nov17-13 03:40 PM lurflurf 5 488 Hi Fellows: If anyone has access to a copy of 'Differential Equations with Boundary-Value Problems (THIRD... Nov17-13 09:54 AM gikiian 2 520 Let A be an 3x3 matrix such that A\mathbf{v_1}=\mathbf{v_1}+\mathbf{v_2}, A\mathbf{v_2}=\mathbf{v_2}+\mathbf{v_3},... Nov16-13 09:11 AM drawar 2 402 For ##\nabla^2 u(r,\theta, \phi)=0##, ##u(r,\theta, \phi)=r^{n}Y_{nm}(\theta,\phi)##. But I have issue with this,... Nov15-13 05:01 PM yungman 0 340 Given a function: z(x,y) = 2x +2y^2 Determine ∂x/∂y , Method 1: x = (z/2) - y^2 ∂x/∂y = -2y Method 2: Nov14-13 07:05 AM SteamKing 8 593 hey pf! does anyone here have a link (or perhaps would care to share some info) on how to solve the biharmonic... Nov13-13 12:57 PM joshmccraney 2 449 Hello - I asked a similar question before, but it was not resolved for me, and the person who answered was rude, so I... Nov11-13 08:39 AM HallsofIvy 3 784