C1_W4_Assignment Example 3 correction

Course Q&A Math for Machine Learning Linear Algebra for Machine Learning and Data Sc...
1

I think there may be a little correction, as shown in the image the matrix A_rotation is rotation by 90 degrees anticlockwise and not the clockwise.

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2

It depends on what coordinate system is used. The assignment doesn’t specify that.

I’ll notify the staff that this either needs an update or clarification.

Thanks!

3

The matrix given in Example 3 seems to be correct if using a right-hand coordinate system (the mathematical standard with the origin in the lower-left corner).

Reference this image from Wikipedia:

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Then clockwise rotation is -90 degrees, and computing the rotation matrix gives the matrix shown in the notebook - because sin(-90) = -1 and cos(- 90) = 0.

4

Thank you, I got it, I was little confused.