C++ atan()用法及代碼示例

該函數在<cmath> 頭文件中定義。

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

atan() 原型 [從 C++ 11 標準開始]

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

參數：

atan() 函數采用單個強製參數(可以是正數、負數或零)

返回：

atan() 函數返回 [-π/2, π/2] 範圍內的值。

示例 1：atan() 如何工作？

#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;
}

運行程序時，輸出將是：

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

示例 2：atan() 具有整數類型的函數

#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;
}

運行程序時，輸出將是：

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