Please post any and all homework or other textbookstyle problems in one of the Homework & Coursework Questions...

Feb2313 09:24 AM
micromass

1 
25,855 
My intent is to create a thread for people interested in Differential Equations. However, I will explicitly state that...

Jul312 07:18 PM
Luccas

95 
121,257 
For a system of linear differential equations with constant coefficients with known initial conditions an analytical...

T 10:26 AM
Mark44

1 
78 
I'm trying to analyze the following Ito stochastic differential equation:
$$dX_t = \X_t\dW_t$$
where X_t,...

Y 06:57 PM
Only a Mirage

2 
125 

 
 
 
Hi everyone,
I'm taking the Differential Equations for the first time, and I want to know the most helpful textbook...

Y 08:12 AM
Bill_K

2 
182 
When I multiply out the first line I end up with an extra (dA/dx)*(dσ/dx). Can someone please show me how i get from...

Apr1714 04:44 PM
Bill_K

1 
125 
I'm having a hard time understanding Green's functions which have been introduced quite early on in the course, and...

Apr1714 01:55 PM
homeomorphic

1 
81 
In this video at around 9:00 , Carl Bender demonstrates a method of solving y''+a(x)y'+b(x)y=0.
...

Apr1714 09:28 AM
chipotleaway

2 
94 
Definition: ##f(x+k) = \exp(k \frac{d}{dx}) f(x)##
So I thought, how take advantage this definition? Maybe it be...

Apr1714 08:19 AM
Jhenrique

2 
135 
Hello I am trying to solve this ODE
dx/dt=(f(x)+g(t))^(1/2)
I have been recalling what I learn in my ODE...

Apr1614 02:16 PM
MathematicalPhysicist

8 
195 
On Wolfram Alpha it will offend give you a contour plot, and it has similarities to a bifurcation plot with respect to...

Apr1514 10:57 PM
JonDrew

0 
75 
I tryied make the convolution product between x² and x³ by ##\int_{ \infty}^{+ \infty} f(u) g(xu) du## and the...

Apr1414 06:20 PM
micromass

5 
170 
I have a differential equation to solve below on the motion of an object oscillating in water with a restoring force...

Apr1414 11:34 AM
the_wolfman

1 
144 
Hello, PF! As I was reading my PChem textbook, I noticed most thermodynamic equations involve partial derivatives,...

Apr1314 08:18 PM
Mark44

3 
174 
I know that the standard definition for a slope field is ##\frac{dy}{dx} = f(x, y)##, but and if the equation given is...

Apr1314 04:08 PM
HallsofIvy

1 
110 
f(x,y) = ln(9  x2  y2)
Domain I got:
(x, y) in R2 such that x2 + y2 < 9
How do I find the range from the...

Apr1214 12:09 PM
JC3187

6 
164 
Show that the explicit RungeKutta scheme
\begin{equation} \frac {y_{n+1} y_{n}}{h}= \frac{1}{2}
\end{equation}...

Apr1014 07:21 PM
rickyflair

2 
168 
If a system of firstorder ODEs like ##\frac{d\vec{r}}{dt}=A\vec{r}## have as solution ##\vec{r} = C_1 \exp(\lambda_1...

Apr1014 02:58 PM
Jhenrique

9 
313 
Hi All,
I am taking Dynamic Systems and Controls this semester for Mechanical Engineering. We are solving non...

Apr914 12:40 AM
MisterX

1 
202 
You can give me a good examples where ##\frac{\partial}{\partial x}## is different to ##\frac{d}{dx}## ?

Apr814 09:12 AM
Jhenrique

2 
200 
Hello
I am having some trouble understanding what the difference is between the reference solution and the "true"...

Apr714 07:36 AM
jjr

2 
244 
Hello guys, suppose we have an eigenvalue problem
\left\{
\begin{array}{ll}
u'' + λu = 0, ...

Apr214 10:44 AM
AlephZero

6 
324 
I realized that a PDE of 2nd order can written like: A:Hf+\vec{b}\cdot\vec{\nabla}f+cf=0
\begin{bmatrix} a_{11} &...

Apr114 09:22 PM
Jhenrique

0 
214 
Hi,
I am looking for a solution of
\frac{\partial\phi}{\partial t} =...

Apr114 06:50 AM
soni

0 
201 
Which the difference between diff equations of kind: \frac{dy}{dx} = \exp(x) \frac{dy}{dx} = 1/x
and diff equations...

Apr114 02:22 AM
Mark44

8 
228 
Hello, I have been trying to find an equation to represent the observed angular velocity of any object traveling in a...

Mar3114 08:50 PM
bendloewen

3 
235 
Hello,
I'm trying to analyze a system of elastically coupled oscillators, whose masses are all the same, using...

Mar3114 10:51 AM
Runei

1 
182 
Hello,
I am doing some physics and I end up with this PDE:
\frac{\partial q(x,y,t)}{\partial t} = (x^2 +...

Mar2814 02:51 PM
kosovtsov

4 
500 
How do we solve a system of coupled differential equations written below?
\frac{d^2}{dr^2}\left(
\begin{array}{c}...

Mar2714 11:04 PM
Ravi Mohan

2 
290 
Given a implicit ODE like F(x, y(x), y'(x), y''(x)) = 0, why your explicit form is y''(x) = f(x, y(x), y'(x))? Why a...

Mar2714 12:36 PM
micromass

4 
242 
If we have a constant coefficient second order homogeneous ODE, the way to solve this is to suppose a solution of the...

Mar2714 08:13 AM
quasar987

4 
230 
hello pf!
i am wondering if anyone here knows of a geometric, intuitive explanation for the laplace transform? if...

Mar2614 05:34 PM
micromass

3 
221 
I would like to learn this. Can someone teach me? The things like δy2/δ2x and solving for x and y. :rolleyes:

Mar2614 12:37 AM
z.js

10 
466 
I want to solve y''+y'+y=(sin(x))^2 and try to use
y=Ae^{ix} but then when I square it I get A^2 e^{2ix}
...

Mar2614 12:26 AM
lurflurf

1 
208 
Hi,
I know the weak form of the Poisson problem
\nabla^2 \phi = f
looks like
\int \nabla \phi \cdot...

Mar2514 01:12 PM
pasmith

1 
224 
It is very clear that the solution to the equation "dy/ya*dx/x = 0" is y=C*x^a. However I cannot figure out the...

Mar2414 05:27 PM
maajdl

5 
227 
Apparently it is a wellknown fact that if G(x)=(G_{ij}(x_1,\ldots,x_n)) is a smooth nxn matrixvalued function such...

Mar2014 03:04 PM
quasar987

0 
360 
px = t
t = s^2
$$ I = \int_0^∞ e^{s^2}ds$$
$$I*I = \int_0^∞ e^{s^2}ds * \int_0^∞ e^{u^2}du = \int_0^∞\int_0^∞...

Mar1914 03:11 PM
HallsofIvy

2 
329 
Hi, this question came up in my midterm and I was hoping to know if this is the correct method or answer.

Mar1814 04:18 PM
pasmith

5 
387 
Hello, I am learning about the general solution to higher order linear nonhomogeneous differential equations. I know...

Mar1714 11:59 PM
lurflurf

1 
304 
I am trying to work though an example on this topic in my book and have reached a point that I am not sure about. I...

Mar1714 04:00 PM
jellicorse

2 
287 