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05 May 2015, 23:18
David Qorashi (8 posts)


I’ve a question about one of the Day 1 exercises.

Q: Brush off your linear algebra knowledge and construct a 90-degree rotation matrix. Try rotating the unit vector [1; 0; 0] by multiplying it by your matrix.

If the given vector was [1; 0] that would be easy. I just needed to multiply it by a 2x2 matrix

I assume that I need to solve the question in 3D space because the vector is in 3D. The problem is that the question doesn’t mention the axis that the rotation should be around it (axis x, y or z).

Am I missing something or there is something wrong with the question.

Thank you so much.

28 Jul 2015, 15:39
Jack Moffitt (5 posts)

It’s a little ambiguously worded, and if you file an errata I’ll make sure to get it updated if/when a new edition is published.

I probably should have explicitly mentioned a 3x3 matrix and said that any axis or handedness would be acceptable.

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