C Math atan2() Function
Example
Return the angle in radians of the polar coordinates given rectangular coordinates:
printf("%f", atan2(0.5, 0.5));
printf("%f", atan2(-0.5, -0.5));
printf("%f", atan2(5, 5));
printf("%f", atan2(10, 20));
printf("%f", atan2(5, -5));
printf("%f", atan2(-10, 10));
Definition and Usage
The atan2() function returns the angle theta in radians from the conversion of rectangular coordinates (x, y) to polar coordinates (r, theta).
This is similar to calling atan(y/x) but it takes into account negative values of x so that it can return angles outside of the range -PI/2 to PI/2.
The atan2() function is defined in the <math.h> header file.
Note: In the atan2() method the y coordinate goes first, then the x coordinate. This is because it is equivalent to the arctangent of the division y / x.
Syntax
One of the following:
atan2(double y, double x);Parameter Values
| Parameter | Description |
|---|---|
| y | Required. The y coordinate of the point to find the angle of. |
| x | Required. The x coordinate of the point to find the angle of. |
Technical Details
| Returns: | A double value representing the angle in radians that a point (x, y) makes around the origin (0, 0). |
|---|
