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C math atan() function

C math atan() function

The C library function double atan(double x) is used to return the arc tangent of x in radians. It takes a single argument as a double and returns the value in radians. This function is defined in <math.h> header file.

Syntax:
`double atan(double x);`

Parameters:-

x − It is the floating point value.

Here is an example of atan() function:
``````
#include <stdio.h>
#include <math.h>
#define PI 3.14159265
int main ()
{
double x, ret, val;
x = 0.75;
val = 180.0 / PI;
ret = atan(x) * val;
printf("The arc tangent of %lf is %lf degrees", x, ret);
return(0);
}
```
```
Output:
The arc tangent of 0.750000 is 36.869898 degrees
Example-2
``````
#include <stdio.h>
#include <math.h>
#define PI 3.14159265
int main ()
{
double x, ret, val;
x = 0.555;
val = 180.0 / PI;
ret = atan(x) * val;
printf("The arc tangent of %lf is %lf degrees", x, ret);
return(0);
}
```
```
Output:
The arc tangent of 0.555000 is 29.030275 degrees