ATAN2(3) Linux Programmer s Manual ATAN2(3)

NAME atan2, atan2f, atan2l - arc tangent function 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);

Link with -lm.

DESCRIPTION The atan2() function calculates the arc tangent of the two variables x and y. It is similar to calculating the arc tangent of y / x, except that the signs of both arguments are used to determine the quadrant of the result.

RETURN VALUE The atan2() function returns the result in radians, which is between -PI and PI (inclusive).

CONFORMING TO SVr4, POSIX.1-2001, 4.3BSD, C89. The float and long double variants are C99 requirements.

SEE ALSO acos(3), asin(3), atan(3), cos(3), sin(3), tan(3)

2002-07-27 ATAN2(3)