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Ordinary or partial differential equations. Delay differential equations, neutral equations, integro-differential equations. Well-posedness, asymptotic behavior, and related questions.
2
votes
Frobenius series of Fuchsian PDEs
I think your questions can be answered by looking at a source that covers singular differential equations of this type, such as R. Gérard and H. Tahara, Singular nonlinear partial differential equatio …
9
votes
General systems of linear differential equations with variable coefficients
Assuming that $A(t)$ is analytic at $t=0$, getting a power series solution $M(t)$ at $t=0$ of $M'(t) = A(t)M(t)$ is trivial, of course. You just write $A(t) = A_0 + A_1 t + \cdots$ and $M(t) = I_n + …
3
votes
Exact or Numerical solutions of a system of differential equatios
This isn't much of an answer, but I thought that I'd put down a few observations here that you may find helpful.
First of all, if $b=0$, then you have a first integral, in that the ratio $x^{3c}/y^ …
2
votes
Accepted
Relation between separation of variables and Hessian properties
The answer is 'no, the first equation does not imply the second when $n=2$'.
The reason is that when $n=2$, the equation is essentially equivalent to requiring that the off-diagonal $n$-by-$n$ block o …
15
votes
Accepted
Any help on one ODE
If you mean a (real) analytical solution with $y(0)=0$, then the answer is 'no'. If you write this as the problem of looking for integral curves of $\omega = (2x-x^2y)\ dx + y\ dy$ in the $xy$-plane, …
9
votes
Looking for the solution of first order non-linear differential equation ($y ′+y^{2}=f(x)$) ...
You are asking about a very classical problem. The Picard-Vessiot theory was developed to show that, in a certain well-defined sense, there is no `closed form' solution to problems of this kind. Yo …
5
votes
Accepted
Partial differential equation parametrization
This is a standard geometric formula, disguised because of the old-fashioned notation and the mixture of the PDE with the formula for exponentiation in the orthogonal group.
Rewrite it this way: S …
2
votes
Accepted
closed integral formula for a non-zero solution of a homogeneous linear ODE of order 2
The answer is basically 'no', there is no 'elementary method' involving elementary operations and quadrature (i.e., finding antiderivatives of known holomorphic functions) that will give you a solutio …
2
votes
How to Separate Charpit Equations
N.B.: I checked your calculations a couple of times, and I got a different sign in the Charpit equations:
$$
-\frac{x}{N^2}dp=-\frac{1}{x^2 y p}dx=\frac{1}{2\Omega x^2 y^2} dy
$$
(Notice the minus si …
4
votes
Accepted
On the solution of a Monge-Ampere type non-linear partial differential equation
When you write the solution, you must have some other conditions in mind, since one generally does not have unique solutions. For example $\zeta = 0$ and $\zeta = 2 w$ both satisfy your equation, so …
4
votes
Accepted
First order PDE, singular at a point
Your conjecture is true, and it can be proved by making a few observations.
First, for each $\alpha\in\mathbb{R}$, let $V_\alpha$ be the vector space of germs of smooth functions $f$ at the origin th …
2
votes
Analytical Solution of Two Simultaneous Partial Differential Equations
There's an obvious analytic answer:
$$
v(x,t) = E\qquad u(x,t) = a E^5 (l-x)
$$
Is that what you wanted?
4
votes
Accepted
Existence of solution to a system of linear PDEs with boundary conditions
The general solution of your equations in a simply connected domain on which $r_2\not=0$ and $r_1\not=\pm1$ is
$$
\beta = \frac12 + \frac1{{(r_1}^2{-}1)}\,
\left(\frac{\partial a}{\partial\theta_1}+b( …
5
votes
Parametric ODEs - when do there exist solutions independent of the parameter?
Depending on what you know about the coefficients $c_{j_0j_1j_2j_3}(\lambda)$, I think that it's not as hopeless as all that.
First of all, such a curve would have to lie in the common zero locus $Z\ …
19
votes
Accepted
Are (Frobenius) integrability conditions covariant?
Your question is a bit vague, but let me try the following statement, which might be the kind of answer you are looking for: If $M$ is a manifold and $S\to M$ is a vector bundle over $M$ endowed with …