NAME
atan2, atan2f,
atan2l —
arc tangent functions of two
variables
SYNOPSIS
#include
<math.h>
double
atan2(double
y, double x);
float
atan2f(float
y, float x);
long double
atan2l(long
double y, long double
x);
DESCRIPTION
The
atan2()
function computes the principal value of the arc tangent of
y/x, using the signs of both
arguments to determine the quadrant of the return value. The
atan2f()
function is a single precision version of atan2().
The
atan2l()
function is an extended precision version of
atan2().
RETURN VALUES
The atan2(),
atan2f() and atan2l()
functions, if successful, return the arc tangent of
y/x in the range
[-pi, +pi] radians. If both x and
y are zero, the global variable
errno is set to EDOM.
SEE ALSO
acos(3), asin(3), atan(3), cos(3), cosh(3), sin(3), sinh(3), tan(3), tanh(3)
STANDARDS
The atan2() function conforms to
ANSI X3.159-1989
(“ANSI C89”).