SOLUTION: A^T denotes the transpose of a matrix A. Show that <A,B> = Tr(B^T,A) defines an inner product on R^(n x n) Let U be the set of symmetric 2 x 2 matrices with real entries. U is

Algebra ->  College  -> Linear Algebra -> SOLUTION: A^T denotes the transpose of a matrix A. Show that <A,B> = Tr(B^T,A) defines an inner product on R^(n x n) Let U be the set of symmetric 2 x 2 matrices with real entries. U is       Log On


   



Question 15127: A^T denotes the transpose of a matrix A.
Show that = Tr(B^T,A) defines an inner product on R^(n x n)
Let U be the set of symmetric 2 x 2 matrices with real entries. U is subspace of R (2x2). Find an orthonormal basis of U with respect to the above inner product.

Answer by khwang(438) About Me  (Show Source):
You can put this solution on YOUR website!
A : nxn square matrix over R. (missing)

A^T denotes the transpose of a matrix A.
Show that = Tr(B^T,A) defines an inner product on R%5E%28n+x+n%29+
Let U be the set of symmetric 2 x 2 matrices with real entries. U is subspace of R (2x2). Find an orthonormal basis of U with respect to the above inner product.
Let A = (aij), B = (bij) be nxn sq. matrices over R. (SIGMA means summation)
Define (A,B) = Tr%28B%5E%28T%29+A%29+= +SIGMA+SIGMA +b%5Bki%5D+a%5Bki%5D+(k=1,2..,n)(i=1,2..,n)

You have to check the definition of inner product (as symmetric
, linear, positive definite, all very easy)

Note the dim of the vector space R%5E%282x2%29 = 4.
And dim U = 3 (why?)
Let A=
(1 0)
(0 0)
B=
(0 0)
(0 1)
C =
(0 1%2Fsqrt%282%29+ )
(1%2Fsqrt%282%29 0)
then {A,B,C} forms an o.n. basis of U.
You should test (A,A)=(B,B)=(C,C)= 1.
(A,B) = (B,C) =(C,A) = 0
Kenny