//Accelerometer angle calculations

1 acc_total_vector = sqrt((acc_x*acc_x)+(acc_y*acc_y)+(acc_z*acc_z)); //Calculate the total accelerometer vector.

2

3if(abs(acc_y) < acc_total_vector){ //Prevent the asin function to produce a NaN

4 angle_pitch_acc = asin((float)acc_y/acc_total_vector)* 57.296; //Calculate the pitch angle.

5}

6 if(abs(acc_x) < acc_total_vector){ //Prevent the asin function to produce a NaN

7 angle_roll_acc = asin((float)acc_x/acc_total_vector)* -57.296; //Calculate the roll angle.

8 }

**WHY THE NEGATIVE SIGN IN LINE 7?**Can anyone clarify this? Thanks.