C++ atan2()

C++ atan2() returns inverse tangent of a coordinate in radians.


The syntax of C++ atan2() is

atan2(x, y)


xX-coordinate value.
yY-coordinate value.


The return value depends on the type of value passed for parameters x and y. The return value of atan2(x, y) is

  • double if x and y are double.
  • float if x and y are float.
  • long double if x and y are long double.

The synopsis of atan2() function is

double atan2(double y, double x);
float atan2(float y, float x);
long double atan2(long double y, long double x);
double atan2(Type1 y, Type2 x); // for combinations of other numeric types

atan2() is a function of cmath library. Include cmath library in the program, if using atan2().


In this example, we read x and y values from the user and find the inverse tangent of this coordinate (x, y) using atan2() function.

C++ Program

#include <iostream>
using namespace std;

int main() {
    double x, y;
    cout << "Enter X : ";
    cin >> x;
    cout << "Enter Y : ";
    cin >> y;
    double result = atan2(x, y);
    cout << "atan2(" << x << ", " << y << ") : " << result << endl;


Enter X : 5
Enter Y : 5
atan2(5, 5) : 0.785398
Program ended with exit code: 0
Enter X : 10
Enter Y : 14.56
atan2(10, 14.56) : 0.601821
Program ended with exit code: 0


In this C++ Tutorial, we learned the syntax of C++ atan2(), and how to use this function to find the inverse tangent of a coordinate, with the help of examples.