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   atanl    ( 3 )

функция арктангенса (arc tangent function)

Имя (Name)

atan, atanf, atanl - arc tangent function

Синопсис (Synopsis)

#include <math.h>

double atan(double x); float atanf(float x); long double atanl(long double x);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

atanf(), atanl(): _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 x; that is the value whose tangent is x.

Возвращаемое значение (Return value)

On success, these functions return the principal value of the arc
       tangent of x in radians; the return value is in the range
       [-pi/2, pi/2].

If x is a NaN, a NaN is returned.

If x is +0 (-0), +0 (-0) is returned.

If x is positive infinity (negative infinity), +pi/2 (-pi/2) 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 │ ├──────────────────────────────────────┼───────────────┼─────────┤ │atan(), atanf(), atanl() │ 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), atan2(3), carg(3), catan(3), cos(3), sin(3),
       tan(3)