# Math Help - Question about gram schmidt process

1. ## Question about gram schmidt process

consider a1 = (1, 1, 2)T and a2 = (-2, 0, 1)T

i am looking for a b3 such that b1 = 1/length(a1) * a1 and b2 = 1/length(a2) * a2

and need a b3 that is orthogonal to these.Why does it not matter if I use (-1, 1 , 4)T (i.e. a1 + a2 with one component changed) or just using e1 (1, 0, 0)T?

2. ## Re: Question about gram schmidt process

Hi bjnovak!

Your Gram-Schmidt process is a little off.
You should have: b2=normalize( a2-(a2.b1)b1 )

Since a 3rd vector a3 is not specified, you can use any vector as long as it is not a linear combination of a1 and a2.
That is, it must point out of the plane defined by a1 and a2 into the 3rd dimension.

Both the vectors you mention satisfy that requirement.