C library function atan() usage and example

C Standard Library <math.h>

The atan() function calculates the arctangent of the parameter.

C atan() function prototype

double atan(double x);

The atan() function takes a single double x as a parameter and returns the value in radians.

The type of the value returned by atan() is double.

To better understand atan():

[Mathematics] tan-1x = atan(x) [In C programming]

It is<math.h>Defined in the header file.

C atan() range

The library function atan() takes any value from negative to positive.

Example: C atan() function

#include <stdio.h>
#include <math.h>
#define PI　3.141592654
int main()
{
　　　　double num =　1.0;
　　　　double result;
　　　　result = atan(num);
　　　　printf("tan(%.2f) The arctangent is = %.2f "radians", num, result);
　　　　//Convert radians to degrees
　　　　result = (result　*　180)}　/　PI;
　　　　printf("\ntan(%2f) The arctangent is = %.2f "degree", num, result);
　　　　return 0;
}

Output Result

cos(1The arctangent of (0.00) is = 0.79　radians
cos(1The arctangent of (0.00) is =　45　degree

C Standard Library <math.h>