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C++ atan2()

In this tutorial, we will learn about the C++ atan2() function with the help of examples.

The atan2() function in C++ returns the inverse tangent of a coordinate in radians. It is defined in the cmath header file.

Mathematically, atan2(y, x) = tan-1(y/x).

Example

#include <iostream>
#include <cmath>
using namespace std;

int main() {

// get the value of tan-1(5.0 / 2.0) cout << atan2(5.0, 2.0);
return 0; } // Output: 1.19029

atan2() Syntax

The syntax of the atan2() function is:

atan2(double y, double x);

atan2() Parameters

The atan2() function takes the following parameters:

  • x - floating-point number that represents the proportion of the x-coordinate
  • y - floating-point number that represents the proportion of the y-coordinate

atan2() Return Value

The atan2() function returns:

  • a floating-point value in the range of [-π, π].
  • 0 if both x and y are zero

atan2() Prototypes

The prototypes of atan2() as defined in the cmath header file are:

double atan2(double y, double x);

float atan2(float y, float x);

long double atan2(long double y, long double x);

// for combinations of arithmetic types
double atan2(Type1 y, Type2 x);

Example 1: C++ atan2()

#include <iostream>
#include <cmath>
using namespace std;

int main() {
  double x = 10.0, y = -10.0;

double result = atan2(y, x);
// convert result to degrees double degree = result * (180 / 3.141592); cout << "atan2(y/x) = " << result << " radians" << endl; cout << "atan2(y/x) = " << degree << " degrees"; return 0; }

Output

atan2(y/x) = -0.785398 radians
atan2(y/x) = -45 degrees

Example 2: C++ atan2() with Different Types

In this program, we will use arguments of different data types with the atan2() function.

#include <iostream>
#include <cmath>
#define PI 3.141592654
using namespace std;

int main() {
  double result;
  float x = -31.6;
  int y = 3;
  
// atan2() with float and int arguments result = atan2(y, x);
cout << "atan2(y/x) = " << result << " radians" << endl; // Display result in degrees cout << "atan2(y/x) = " << result * (180 / PI) << " degrees"; return 0; }

Output

atan2(y/x) = 3.04694 radians
atan2(y/x) = 174.577 degrees
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