How can I rotate a curve deformed using python, without compromising its shape ?
Please help me ! :cry:

Try buildRotateAboutAxis(axis, angle_in_deg):

http://www.sidefx.com/docs/houdini11.0/hom/hou/hmath [sidefx.com]

Once you've built a transform matrix using either rotateAboutAxis, extracting it from some object or creating it yourself using hmath you can then either call hou.Geometry.transform(), or transformPrims() if your geometry has other things that aren't your curve. Another option is to take the point position of each point on the curve, multiply its position by the xform matrix and set it back. This method however will not transform any vector point attributes on those points so if you have attributes you should go with the transform functions on hou.Geometry.

I will use the function buildRotateAboutAxis and make some modifications to the code , I want to guide this curve with two NULLs !