Most probably a Thing (mix up) with rad (0...2pi) vs. degree (0...360)?
Read this:
Math.Cos-Methode: (Double) (System)[
^]
Especally Remarks: The angle, d, must be in radians. Multiply by Math.PI/180 to convert degrees to radians.
What does it mean:
VectorMath :: Rotate(v, axis, 40.0)
vs.
VectorMath :: Rotate(v, axis, 40.0 * Math.PI/180.0)
Hope it helps.