phoenix-rtos-doc / libc / functions / c / cos.part-impl.md

cos

Synopsis

#include <math.h>

double cos(double x);

float cosf(float x);

Status

Partially implemented

Conformance

IEEE Std 1003.1-2017

Description

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.

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.

Errors

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.

Tests

Untested

Known bugs

None

cos