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)      (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   
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. (  means summation) 
 Define (A,B) =  =     (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   = 4. 
 And dim U = 3 (why?) 
 Let A= 
 (1 0) 
 (0 0) 
 B= 
 (0 0) 
 (0 1) 
 C = 
 (0   ) 
 (  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 
 
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