- #1
steelphantom
- 159
- 0
Homework Statement
Make P2(R) into an inner-product space by defining <p, q> = [tex]\int_0^1p(x)q(x)dx[/tex]. Define T in L(P2(R)) by T(a_0 + a_1*x + a_2*x2) = a_1*x.
(a) Show that T is not self-adjoint.
(b) The matrix of T with respect to the basis (1, x, x2) is
[tex]\left(
\begin{array}{ccc}
0 & 0 & 0\\
0 & 1 & 0\\
0 & 0 & 0
\end{array}
\right)[/tex]
This matrix equals its conjugate transpose, even though T is not self-adjoint. Explain why this is not a contradiction.
Homework Equations
The Attempt at a Solution
To show that T is not self-adjoint, I need to show that T != T*. This amounts to explicitly finding what T* is. I know that <Tv, w> = <v, T*w>.
So we have <T(a_0 + a_1*x + a_2*x2), b_0 + b_1*x + b_2*x2> = <a_1*x, b_0 + b_1*x + b_2*x2> = a_1*x(b_0 + b_1*x + b_2*x2). Now I can't quite figure out where to go from here. I know this has to equal <a_0 + a_1*x + a_2*x2, T*(b_0 + b_1*x + b_2*x2)>. How can I find T*?
For part (b), I know that a if an operator is self-adjoint, its matrix equals its conjugate transpose, but not necessarily the other way around. This is a crappy way of putting it, though. Maybe I'll have a better explanation once I find T*. Thanks for any help!