Exercise 5.6.4

Show that a product of unitary (orthogonal) matrices is unitary (orthogonal) as well.

Answers

Proof. Suppose U1,U2 are unitary (orthogonal), then

(U1U2)U 1U2 = U2U 1U 1U2 = U2IU 2 = I.

From Lemma 6.2, we know the product is unitary (orthogonal). □

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2018-11-29 00:00
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