atan2(), atan2f()

Computes the arctangent, determining the quadrant

Synopsis:

#include <math.h>

double atan2( double y, 
              double x );

float atan2f( float y, 
              float x );

Library:

libm

Description:

These functions compute the value of the arctangent (specified in radians) of y/x, using the signs of both arguments to determine the quadrant of the return value. A domain error occurs if both arguments are zero.

Returns:

The arctangent of y/x, in the range (-PI, PI).

Examples:

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

int main( void )
{
    printf( "%f\n", atan2( .5, 1. ) );

    return EXIT_SUCCESS;
}

produces the output:

0.463648

Classification:

ANSI

See also:

acos(), asin(), atan(), errno