Simple, construct a basis of R2 with an inner product

Click For Summary
SUMMARY

The discussion focuses on constructing an orthogonal basis for R2 using a non-standard inner product defined by the matrix A = [[2, 1], [1, 3]]. The user initially attempts to use the canonical basis (1,0) and (0,1) but encounters difficulties in satisfying the inner product conditions. After exploring various vectors, the user identifies a potential basis of (1 - [1+sqrt(5)]/2, [1+sqrt(5)]/2) and (1, 1), which appears to be linearly independent. The next step involves orthogonalizing this basis using the Gram-Schmidt process.

PREREQUISITES
  • Understanding of inner product spaces and their properties
  • Familiarity with matrix operations and eigenvalues
  • Knowledge of the Gram-Schmidt orthogonalization process
  • Basic linear algebra concepts, particularly vector independence
NEXT STEPS
  • Study the Gram-Schmidt process for orthogonalizing vectors in R2
  • Explore the properties of non-standard inner products in vector spaces
  • Learn about matrix representations of inner products and their implications
  • Investigate the geometric interpretation of orthogonal bases in R2
USEFUL FOR

Students and educators in linear algebra, mathematicians working with inner product spaces, and anyone interested in advanced vector space concepts.

simpledude
Messages
20
Reaction score
0

Homework Statement


Construct an orthogonal basis of R2 equipped with the non-standard inner product defined for all X, Y belonging to R2, by

<X,Y> = X^T AY
with
A =
2 1
1 3

The Attempt at a Solution


So it seems pretty trivial, but I can't seem to get the answer. So my approach is
1) First get any basis that fits with this inner product
2) Use Gram-Scmidt to orthogonalize that basis

So I know I can start with the canonical basis of R2: (1,0) (0,1)
My problem is, how can I satisfy the inner product if I start from the canonical basis?

I have also attempted to solve the equations of two arbitrary vectors v1, v2
where v1=(x1, y2) and v2=(x2,y2) and given the matrix A we know:
x1x2 + y1y2 = 1
x1^2 + y1^2 = 2
x2^2 + y2^2 = 3
But if I plug in the canoical basis for v1, the solution fails. It only works when both points are non-zero, i.e. v1 = (1, 1)Any help would be appreciated.

EDIT:
Actually now that I am looking at my solution, I obtained (via my method of substituting (1,1) for x1, y1 in my equations) the basis that works with this inner product as:
( 1 - [1+sqrt(5)]/2 , [1+sqrt(5)]/2 ) and (1, 1)

They seem to be linearly independent, did I do this right? (I know I still have to orthogonalize them)
 
Last edited:
Physics news on Phys.org
Anyone?
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 16 ·
Replies
16
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
3
Views
2K