What is not easy is the integration beacause even if I'm ok with the math, the computation will get some errors at every calculation and these errors will accumulate giving me a rising integral even if the accelerometer is not moving. I tried all the logic stuff (semplification, casting, etc...), nothing worked, so I'm here to ask your help.
No it's so easy by Numerical computations method
Rectangle Rule
Trapezoidal Rule
Simpson's Rule
Newton's 3/8 Rule
first apply those in matlab then port them in arduino 