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Question

Math 6410 • ODE

Spring 2017 • Question 7

The Ornstein-Uhlenbeck (OU) differential equation is \[ \frac {\partial p}{\partial t} =\frac {\partial }{\partial x}(kxp)+D\frac {\partial ^2p}{\partial x^2}. \]

  1. What type of partial differential equation is this? What calculation is needed to justify this statement?
  2. If \(t\) has units of time and \(x\) has units of length, what are the units of the parameters \(k\) and \(D\)?
  3. Express this equation in nondimensional variables? How many nondimensional parameters remain after nondimensionalization?
  4. Find the solution of the OU equation on the domain \(-\infty <x<\infty \), \(t\ge 0\) with initial data \(p(x,0)=\delta (x-x_0)\) for arbitrary \(x_0\). Give an interpretation of this solution in terms of a probability.

Raw LaTeX

The Ornstein-Uhlenbeck (OU) differential equation is
\[
  \frac{\partial p}{\partial t}
  =\frac{\partial}{\partial x}(kxp)+D\frac{\partial^2p}{\partial x^2}.
\]
\begin{enumerate}
\item[(a)] What type of partial differential equation is this? What calculation is
needed to justify this statement?
\item[(b)] If \(t\) has units of time and \(x\) has units of length, what are the units
of the parameters \(k\) and \(D\)?
\item[(c)] Express this equation in nondimensional variables? How many nondimensional
parameters remain after nondimensionalization?
\item[(d)] Find the solution of the OU equation on the domain \(-\infty<x<\infty\),
\(t\ge0\) with initial data \(p(x,0)=\delta(x-x_0)\) for arbitrary \(x_0\). Give an
interpretation of this solution in terms of a probability.
\end{enumerate}