Orthonormal Bases
Now that we have the Gram-Schmidt process as a tool, we can use it to come up with orthonormal bases.
Any vector space with finite dimension
has a finite basis
. This is exactly what it means for
to have dimension
. And now we can apply the Gram-Schmidt process to turn this basis into an orthonormal basis
.
We also know that any linearly independent set can be expanded to a basis. In fact, we can also extend any orthonormal collection of vectors to an orthonormal basis. Indeed, if is an orthonormal collection, we can add the vectors
to fill out a basis. Then when we apply the Gram-Schmidt process to this basis it will start with
, which is already normalized. It then moves on to
, which is orthonormal with
, and so on. Each of the
is left unchanged, and the
are modified to make them orthonormal with the existing collection.
