# atan2 function(Arc Tangent of Quotient) in C Language – example and detail

In the C Programming Language, the atan2 function returns the arc tangent of y / x.

## Syntax

The syntax for the atan2 function in the C Language is:

``double atan2(double y, double x);``

Parameters or Arguments

x The parameter when calculating the arc tangent of y / x. y The parameter when calculating the arc tangent of y / x.

## Returns

The atan2 characteristic returns the arc tangent of y / x. It will return a value between -π and π. If x and y are each equal to 0, the atan2 function will return a area error.

In the C Language, the required header for the atan2 characteristic is:

``#include <math.h>``

## Applies To

In the C Language, the atan2 characteristic can be used in the following versions:

ANSI/ISO 9899-1990

## atan2 Example

``````/* Example using atan2 by TechOnTheNet.com */

#include <stdio.h>
#include <math.h>

int main(int argc, const char * argv[])
{
/* Define temporary variables */
double value1, value2;
double result;

/* Assign the two values we will find the atan2 of */
value1 = 0.5;
value2 = -0.5;

/* Calculate the Arc Tangent of value1 and value2 */
result = atan2(value1, value2);

/* Display the result of the calculation */
printf("The Arc Tangent of %f and %f is %f\n", value1, value2, result);

return 0;
}``````

When compiled and run, this utility will output:

``The Arc Tangent of 0.500000 and -0.500000 is 2.356194``

## Similar Functions

Other C functions that are comparable to the atan2 function:

acos feature asin function atan feature cos feature sin feature tan function