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Question

Math 6420 • PDE

Spring 2014 • Question 3

Consider the problem \(u''(x)=f(x)\), on \((0,1)\), with boundary conditions \(u'(0)=u'(1)=0\).

  1. Write down the weak formulation of the problem.
  2. Using a piecewise linear finite element basis with uniform grid size \(h\), use the Galerkin method to find a finite-dimensional (matrix) approximate representation for the problem. Do not solve the equations.
  3. Neither of the problems (a) and (b) have unique solutions in general. Explain why not, and describe what can be done to correct the deficiency.

Raw LaTeX

Consider the problem \(u''(x)=f(x)\), on \((0,1)\), with boundary conditions
\(u'(0)=u'(1)=0\).
\begin{enumerate}
\item[(a)] Write down the weak formulation of the problem.

\item[(b)] Using a piecewise linear finite element basis with uniform grid size \(h\), use the
Galerkin method to find a finite-dimensional (matrix) approximate representation for the
problem. Do not solve the equations.

\item[(c)] Neither of the problems (a) and (b) have unique solutions in general. Explain why
not, and describe what can be done to correct the deficiency.
\end{enumerate}