C++ Reference Manual

C++ Library Function <cmath>

C ++cos() Function Usage and Example

This function returns the cosine value of the angle (parameter) expressed in radians.<cmath>Defined in the header file.

[Mathematics] cos x = cos(x) [C++]

cos() prototype (from C ++ 11Standard beginning)

double cos(double x);
float cos(float x);
long double cos(long double x);
double cos(T x);　//Here, T is an integer type.

cos() parameter

The cos() function takes a mandatory parameter in radians.

The value returned by cos()

The cos() function returns[-1,1]The returned value is double, float, or long double.

Example1How to use cos() in C ++Working in the middle?

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
　　double x = 0.5, result;
　　
　　result = cos(x);
　　cout << "cos(x) = " << result << endl;
　　
　　double xDegrees =　25;
　　
　　//Convert angles to radians
　　x = xDegrees*3.14159/180;
　　result = cos(x);
　　
　　cout << "cos(x) = " << result << endl;
　　return 0;
}

When the program is run, the output is:

cos(x) = 0.877583
cos(x) = 0.906308

Example2: The cos() function with integer type

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
　　int x =　1;
　　double result;
　　result = cos(x);
　　cout << "cos(x) = " << result << endl;
　　
　　return 0;
}

When the program is run, the output is:

cos(x) = 0.540302

　 C++ Library Function <cmath>