Calculate atan2 without std functions or C99

Question

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

Answer 1

The actual implementations of the math functions (or stubs to the HWFPU if one exists) should be in libm. With GCC this is indicated by passing -lm to the compiler, but I don't know how it is done with your specific tools.