I am calculating angles from a 3-axis accelerometer, but my compiler doesn't have a atan or atan2 function. It has a reserved memory slot, but it calls a function i can't find in any files.
My compiler is Keil µVision 4 running the ARMCC compiler. The compiles has the file math.h, but the function is extern and doesn't exist:
extern _ARMABI double atan2(double /*y*/, double /*x*/);
Is there a lib or function I can include that has the function arctan implemented? Or is there an alternative function to calculate angles from accelerometer? I need full 3-axis calibration of the angles.
Edit: I was hoping to avoid a table full of pre-calculated values.