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.


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.


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.

Required Header

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 */

#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