Today

• Orthogonal Projection (cont’d).

• HW5 due Nov 19 Friday @ 11:59pm on Gradescope/CCLE.

• HW5 Q1: typo (corrected).

• HW Q7: It’s fine to use computer to obtain answer. Strategy 1: run GS on $A$ to obtain an orthonormal basis $Q_A$ of $C(A)$; run GS on $I - Q_A Q_A’$ to obtain an orthonormal basis of $N(A’)$; run GS on $A’$ to obtain an orthonormal basis $Q_{A’}$ of $C(A’)$; run GS on $I - Q_{A’}Q_{A’}’$ to obtain an orthonormal basis of $N(A)$. Strategy 2: singular value decomposition of $A$ gives all we need.

• Midterm common questions: Q4.6, Q4.5, Q3.