184: Matrix Transform
Title text: In fact, draw all your rotational matrices sideways. Your professors will love it! And then they'll go home and shrink.
A rotational matrix transformation (i.e. the big brackets with a few "cos" and "sin" in them) is used in computer graphics to rotate an image. The product of the transform matrix and the argument vector (a1, a2) is a rotated version of the argument vector, which should be noted as (a1', a2').
The joke is that the author turned the image of the vector rather than writing the correct answer. Rotational matrix transformations are a special case of the general linear matrix transform, which can do other things to images, including shrinking them. In this case the matrix would rotate the image 90 degrees clockwise.
At the title text we see that the professors even shrinking at home on this joke.
- [A square matrix next to a vertical two-by-one matrix, equated to a horizontal matrix that looks like the two-by-one matrix turned 90 degrees.]
- [Square matrix:
- cos90° sin90°
- -sin90° cos90°]
- [Two by one matrix:
- [An equal sign]
- [The same two by one matrix, but rotated by 90 degrees clockwise:
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