atan2()

Using Arduino Programming Questions
#1

So, I want to calculate the heading of a moving object and this is what I found:

double heading(double x, double y) {
  double head = atan2(y, x); // Slope Y, Slope X
  return head;
}

So what I wanted to know is what is the output of the function atan2().

Thank you in advance.

#2

Bakr:
So what I wanted to know is what is the output of the function atan2().

So look up the expected parameters and the return value in the AVR LIBC manual of atan2()

#3

short answer, the angle in radians

#4

Think of an xy plane, if you have a vector that goes from 0 to 1,1 then the magnitude will be the sqrt(2) and the angle will be 45 degrees. atan2 takes the x and the y and returns the 45 degrees. It needs x and y so it will be correct for the whole circle. if you pass it just the ratio of x and y, it cannot determine the quadrant. In this case, if it did not take x and y into account it could be 1,1 or -1,-1.

But atan2() returns radians, not degrees.

#5