A9_soln

# A9_soln - Math 235 Assignment 9 Solutions 1 Let ~u =(1 i 2...

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Unformatted text preview: Math 235 Assignment 9 Solutions 1. Let ~u = (1 + i, 2- i ) and ~v = (3- i, 3 + i ). Use the standard inner product on C n to calculate < ~u,~v > , < ~v,~u > , and k ~v k . Solution: We have < ~u,~v > = (1 + i, 2- i ) · (3- i, 3 + i ) = (1 + i )(3 + i ) + (2- i )(3- i ) = 2 + 4 i + 5- 5 i = 7- i < ~v,~u > = (3- i, 3 + i ) · (1 + i, 2- i ) = (3- i )(1- i ) + (3 + i )(2 + i ) = 2- 4 i + 5 + 5 i = 7 + i k ~v k = p < ~v,~v > = q (3- i, 3 + i ) · (3- i, 3 + i ) = p (3- i )(3 + i ) + (3 + i )(3- i ) = √ 20 2. Determine which of the following matrices is unitary. a) A = (1 + i ) / √ 7- 5 / √ 35 (1 + 2 i ) / √ 7 (3 + i ) / √ 35 . Solution: Observe that Solution: Let ~u = ((1 + i ) / √ 7 , (1 + 2 i ) / √ 7), and ~v = (- 5 / √ 35 , (3 + i ) / √ 35). Then we have < ~u,~u > = 1 7 [(1 + i )(1- i ) + (1 + 2 i )(1- 2 i )] = 1 7 [2 + 5] = 1 < ~v,~v > = 1 35 [(- 5)(- 5) + (3 + i )(3- i )] = 1 35 [25 + 10] = 1 < ~u,~v > = 1 √ 7 √ 35 [(1 + i )(- 5) + (1 + 2 i )(3- i )] = 1 √ 7 √ 35 [- 5- 5 i + 5 + 5 i ] = 0 Hence, { ~u,~v } is an orthonormal basis for C 2 and so...
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## This note was uploaded on 04/18/2010 for the course MATH 235 taught by Professor Celmin during the Spring '08 term at Waterloo.

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A9_soln - Math 235 Assignment 9 Solutions 1 Let ~u =(1 i 2...

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