Paper 4, Section I, F

Linear Algebra
Part IB, 2010

Define the notion of an inner product on a finite-dimensional real vector space VV, and the notion of a self-adjoint linear map α:VV\alpha: V \rightarrow V.

Suppose that VV is the space of real polynomials of degree at most nn in a variable tt. Show that

f,g=11f(t)g(t)dt\langle f, g\rangle=\int_{-1}^{1} f(t) g(t) d t

is an inner product on VV, and that the map α:VV\alpha: V \rightarrow V :

α(f)(t)=(1t2)f(t)2tf(t)\alpha(f)(t)=\left(1-t^{2}\right) f^{\prime \prime}(t)-2 t f^{\prime}(t)

is self-adjoint.