C++ atan()

此函数定义在 <cmath> 头文件中。

[Mathematics] tan-1x = atan(x) [In C++ Programming];

atan() 原型 [截至 C++ 11 标准]

double atan(double x);
float atan(float x);
long double atan(long double x);
double atan (T x); // For integral type

atan() 参数

atan() 函数接受一个必需参数（可以是正数、负数或零）

atan() 返回值

atan() 函数返回 **[-π/2, π/2]** 范围内的值。

示例 1：atan() 的工作原理？

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
  double x = 57.74, result;
  result = atan(x);
  
  cout << "atan(x) = " << result << " radians" << endl;
  
  // Output in degrees
  cout << "atan(x) = " << result*180/3.1415 << " degrees" << endl;
  
  return 0;
}

运行程序后，输出将是

atan(x) = 1.55348 radians
atan(x) = 89.0104 degrees

示例 2：带整数类型的 atan() 函数

#include <iostream>
#include <cmath>
#define PI 3.141592654

using namespace std;

int main()
{
  int x = 14;
  double result;
  
  result = atan(x);
  
  cout << "atan(x) = " << result << " radians" << endl;
  // Output in degrees
  cout << "atan(x) = " << result*180/3.1415 << " degrees" << endl;
  
  return 0;
}

运行程序后，输出将是

atan(x) = 1.49949 radians
atan(x) = 85.9169 degrees

另请阅读

• C++ tan()
• C++ atan2()