Thanks David.
1) r = RotationMatrix[theta] worked fine. If I wanted to try different matrices, for example
{{Cos[theta], Sin[theta]}, {-Sin[theta], Cos[theta]}}
how would I do that?
2) When I input r.{x, y} I got
out[55]= {x Cos[theta] - Sqrt[1 - x^2] Sin[theta], Sqrt[1 - x^2] Cos[theta] + x Sin[theta]}
Not sure whats different?
Thanks
Alan
