Exercise 1055Linear algebra › Matrices and linear systemsL1Added 3 Nov 2026
Gram-Schmidt orthogonalization
#Gram-Schmidt#orthogonalization#orthonormal basis
Statement
Apply Gram-Schmidt to the vectors v1=(1,1,0), v2=(1,0,1), v3=(0,1,1) in R3.
Hint
At each step, subtract from vk its projection onto the previously constructed orthonormal vectors.
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Solution
Step 1.u1=v1/∥v1∥=(1,1,0)/2.
Step 2. Projection of v2 onto u1: ⟨v2,u1⟩=1/2. So w2=v2−(1/2)u1=(1,0,1)−(1/2)(1,1,0)=(1/2,−1/2,1). Norm: 1/4+1/4+1=3/2, so u2=(1/6,−1/6,2/3).
Step 3. Projections of v3: ⟨v3,u1⟩=1/2,⟨v3,u2⟩=(−1+1+2)/6=2/6. So w3=v3−(1/2)u1−(2/6)u2=(0,1,1)−(1/2)(1,1,0)−(1/3)(1,−1,2)=(1/6,5/6,1/3). Norm: 1/36+25/36+4/36=30/6, so u3=6/5(1/6,5/6,1/3)=(1/30,5/30,2/30).
Conclusion. The orthonormal basis is u1=21(1,1,0),u2=61(1,−1,2),u3=301(1,5,2).