InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
How Do I Rotate A 2d Point? |
|
Answer» In 2-D, the 2x2 matrix is very simple. If you WANT to ROTATE a column vector V by t degrees using matrix M, use M = {{cos t, -sin t}, {sin t, cos t}} in M*v. If you have a row vector, use the transpose of M (TURN rows into columns and vice VERSA). If you want to combine rotations, in 2-D you can just add their angles, but in higher dimensions you must multiply their matrices. In 2-D, the 2x2 matrix is very simple. If you want to rotate a column vector v by t degrees using matrix M, use M = {{cos t, -sin t}, {sin t, cos t}} in M*v. If you have a row vector, use the transpose of M (turn rows into columns and vice versa). If you want to combine rotations, in 2-D you can just add their angles, but in higher dimensions you must multiply their matrices. |
|