iPhone, how to calculate iPhone device three axis angle via UIAcceleration ?

Question

as topic,

I am try to use the code as follows :

xAngle = 90.0 *x; yAngle = 90.0* y; zAngle = 90.0* z;

but seem it is not right (x,y,z is the UIAcceleration attributes x, y and z)

am I miss some thing in this algorithm ?

thanks for your help

Best .