<cmath>
double atan2 ( double y, double x );
long double atan2 ( long double y, long double x );
float atan2 ( float y, float x );
Compute arc tangent with two parameters
Returns the principal value of the arc tangent of y/x, expressed in radians.
To compute the value, the function uses the sign of both arguments to determine the quadrant.
In C++, this function is overloaded in <valarray> (see valarray atan2).
Parameters
- y
- Floating point value representing an y-coordinate.
- x
- Floating point value representing an x-coordinate.
If both arguments passed are zero, a domain error occurs, which sets the global variable ERRNO to the EDOM value.
Return Value
Principal arc tangent of y/x, in the interval [-pi,+pi] radians.
Portability
In C, only the double version of this function exists with this name.
Example
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
|
/* atan2 example */
#include <stdio.h>
#include <math.h>
#define PI 3.14159265
int main ()
{
double x, y, result;
x = -10.0;
y = 10.0;
result = atan2 (y,x) * 180 / PI;
printf ("The arc tangent for (x=%lf, y=%lf) is %lf degrees\n", x, y, result );
return 0;
}
|
Output:
The arc tangent for (x=-10.000000, y=10.000000) is 135.000000 degrees.
|
See also
| atan | Compute arc tangent (function) |
| tan | Compute tangent (function) |
| sin | Compute sine (function) |
| cos | Compute cosine (function) |
|