c99 [ flag... ] file... –lm [ library... ] #include <math.h> double cos(double x);
float cosf(float x);
long double cosl(long double x);
These functions compute the cosine of x, measured in radians.
Upon successful completion, these functions return the cosine of x.
If x is NaN, NaN is returned.
If x is +0, 1.0 is returned.
If x is ±Inf, a domain error occurs and a NaN is returned.
These functions will fail if:
The x argument is ±Inf.
If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the invalid floating-point exception is raised.
An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions.
See attributes(5) for descriptions of the following attributes: