арктангенс функция двух переменных (arc tangent function of two variables)
Имя (Name)
atan2, atan2f, atan2l - arc tangent function of two variables
Синопсис (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.
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
atan2f(), atan2l():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Описание (Description)
These functions calculate the principal value of the arc tangent
of y/x, using the signs of the two arguments to determine the
quadrant of the result.
Возвращаемое значение (Return value)
On success, these functions return the principal value of the arc
tangent of y/x in radians; the return value is in the range
[-pi, pi].
If y is +0 (-0) and x is less than 0, +pi (-pi) is returned.
If y is +0 (-0) and x is greater than 0, +0 (-0) is returned.
If y is less than 0 and x is +0 or -0, -pi/2 is returned.
If y is greater than 0 and x is +0 or -0, pi/2 is returned.
If either x or y is NaN, a NaN is returned.
If y is +0 (-0) and x is -0, +pi (-pi) is returned.
If y is +0 (-0) and x is +0, +0 (-0) is returned.
If y is a finite value greater (less) than 0, and x is negative
infinity, +pi (-pi) is returned.
If y is a finite value greater (less) than 0, and x is positive
infinity, +0 (-0) is returned.
If y is positive infinity (negative infinity), and x is finite,
pi/2 (-pi/2) is returned.
If y is positive infinity (negative infinity) and x is negative
infinity, +3*pi/4 (-3*pi/4) is returned.
If y is positive infinity (negative infinity) and x is positive
infinity, +pi/4 (-pi/4) is returned.
Ошибки (Error)
No errors occur.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│atan2(), atan2f(), atan2l() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD, C89.
Смотри также (See also)
acos(3), asin(3), atan(3), carg(3), cos(3), sin(3), tan(3)
