функция косинуса (cosine function)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
cos, cosf, cosl — cosine function
Синопсис (Synopsis)
#include <math.h>
double cos(double x);
float cosf(float x);
long double cosl(long double x);
Описание (Description)
The functionality described on this reference page is aligned
with the ISO C standard. Any conflict between the requirements
described here and the ISO C standard is unintentional. This
volume of POSIX.1‐2017 defers to the ISO C standard.
These functions shall compute the cosine of their argument x,
measured in radians.
An application wishing to check for error situations should set
errno to zero and call feclearexcept(FE_ALL_EXCEPT) before
calling these functions. On return, if errno is non-zero or
fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
FE_UNDERFLOW) is non-zero, an error has occurred.
Возвращаемое значение (Return value)
Upon successful completion, these functions shall return the
cosine of x.
If x is NaN, a NaN shall be returned.
If x is ±0, the value 1.0 shall be returned.
If x is ±Inf, a domain error shall occur, and a NaN shall be
returned.
Ошибки (Error)
These functions shall fail if:
Domain Error
The x argument is ±Inf.
If the integer expression (math_errhandling &
MATH_ERRNO) is non-zero, then errno shall be set to
[EDOM]. If the integer expression (math_errhandling
& MATH_ERREXCEPT) is non-zero, then the invalid
floating-point exception shall be raised.
The following sections are informative.
Примеры (Examples)
Taking the Cosine of a 45-Degree Angle
#include <math.h>
...
double radians = 45 * M_PI / 180;
double result;
...
result = cos(radians);
Использование в приложениях (Application usage)
These functions may lose accuracy when their argument is near an
odd multiple of π/2 or is far from 0.
On error, the expressions (math_errhandling & MATH_ERRNO) and
(math_errhandling & MATH_ERREXCEPT) are independent of each
other, but at least one of them must be non-zero.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
acos(3p), feclearexcept(3p), fetestexcept(3p), isnan(3p),
sin(3p), tan(3p)
The Base Definitions volume of POSIX.1‐2017, Section 4.20,
Treatment of Error Conditions for Mathematical Functions,
math.h(0p)
