# Explaining why a set of orthonormal vectors spans a subspace

• Mar 30th 2013, 03:05 PM
twilightmage13
Explaining why a set of orthonormal vectors spans a subspace
Suppose we have a subspace V spanned by the basis {1, x, x^2, x^3, sin(x)}.

By applying the Gram-Schmidt process to the above basis, we obtain an orthonormal basis {z1, z2, z3, z4, z5}.

Why does this orthonormal basis span the same subspace V (that was spanned by the non-orthonormal vectors)?
• Mar 30th 2013, 03:43 PM
SworD
Re: Explaining why a set of orthonormal vectors spans a subspace
Because the orthonormal basis members are linear combinations of the original vectors, so by adjusting coefficients you can span the same subspace.

I feel like this was a very short explanation, someone could probably provide a better one :p
• Mar 30th 2013, 04:02 PM
HallsofIvy
Re: Explaining why a set of orthonormal vectors spans a subspace
I think it was very nicely stated!
• Mar 30th 2013, 06:07 PM
twilightmage13
Re: Explaining why a set of orthonormal vectors spans a subspace
I think it's starting to make sense, thank you! Would you mind explaining how we can determine the weights to express the orthonormal vectors as linear combinations of the original vectors?