C++ atan2Usage and example of the function

C++ Library Function <cmath>

C ++The atan function2The function returns the arctangent of the coordinates in radians.

This function returns<cmath>defined in the header file.

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

atan2The prototype[from C ++ 11Standard library]

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 the combination of arithmetic types.

atan2The parameters

The atan function2The function has two parameters: x coordinate and y coordinate.

• x -This value represents the proportion of the x coordinate.

• y -This value represents the proportion of the y coordinate.

atan2The return value

atan2The function returns[-π, π]Values in the range. If both x and y are zero, then atan2The function will return 0.

Example1: atan2How to work with x and y of the same type?

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
　　double x =　10.0, y =　-10.0, result;
　　result = atan2(y, x);
　　
　　cout << "atan2(y/x) = " << result << " radians" << endl;
　　cout << "atan2(y/x) = " << result*180/3.141592　<< "degrees" << endl;
　　
　　return 0;
}

When running the program, the output is:

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

Example2: atan2How to use with different types of x and y?

#include <iostream>
#include <cmath>
#define PI　3.141592654
using namespace std;
int main()
{
　　double result;
　　float x =　-31.6;
　　int y =　3;
　　
　　result = atan2(y, x);
　　
　　cout << "atan2(y/x) = " << result << " radians" << endl;
　　//Display the result in degrees
　　cout << "atan2(y/x) = " << result*180/PI << " degrees";
　　return 0;
}

When running the program, the output is:

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

　 C++ Library Function <cmath>