Finding rotational angle: expression2

[Mixed Sources]

Im having a few problems with finding the rotational angle using expression 2.

If i use it as a gyro outputting yaw roll and pitch then the variables are altered if say the chip is not perpendicular to the floor (for example if i wanted to find roll).

If there is a command line to find the rotation around a particular axis (ie the degrees of rotation on the X axis of the E2 chip, and not in relation to the world) Could i get a hand with this?

Thanks in advance.