std::cos,std::cosf,std::cosl(3)

NAME
std::cos,std::cosf,std::cosl - std::cos,std::cosf,std::cosl

Synopsis
   Defined in header <cmath>
   float cos ( float arg );
   float cosf( float arg ); (since C++11)
   double cos ( double arg ); (1) (2)
   long double cos ( long double arg );
   long double cosl( long double arg ); (3) (since C++11)
   double cos ( IntegralType arg ); (4) (since C++11)
   1-3) Computes the cosine of arg (measured in radians).
   4) A set of overloads or a function template accepting an argument of any integral
   type. Equivalent to 2) (the argument is cast to double).

Parameters
   arg - value representing angle in radians, of a floating-point or Integral type

Return value
   If no errors occur, the cosine of arg (cos(arg)) in the range [-1 ; +1], is
   returned.
   The result may have little or no significance if the magnitude of arg (until C++11)
   is large
   If a domain error occurs, an implementation-defined value is returned (NaN where
   supported)
   If a range error occurs due to underflow, the correct result (after rounding) is
   returned.

Error handling
   Errors are reported as specified in math_errhandling.
   If the implementation supports IEEE floating-point arithmetic (IEC 60559),
     * if the argument is ±0, the result is 1.0
     * if the argument is ±∞, NaN is returned and FE_INVALID is raised
     * if the argument is NaN, NaN is returned

Notes
   The case where the argument is infinite is not specified to be a domain error in C,
   but it is defined as a domain error in POSIX

Example
// Run this code
 #include <iostream>
 #include <cmath>
 #include <cerrno>
 #include <cfenv>
 #pragma STDC FENV_ACCESS ON
 const double pi = std::acos(-1);
 int main()
 {
     // typical usage
     std::cout << "cos(pi/3) = " << std::cos(pi/3) << '\n'
               << "cos(pi/2) = " << std::cos(pi/2) << '\n'
               << "cos(-3*pi/4) = " << std::cos(-3*pi/4) << '\n';
     // special values
     std::cout << "cos(+0) = " << std::cos(0.0) << '\n'
               << "cos(-0) = " << std::cos(-0.0) << '\n';
     // error handling
     std::feclearexcept(FE_ALL_EXCEPT);
     std::cout << "cos(INFINITY) = " << std::cos(INFINITY) << '\n';
     if (std::fetestexcept(FE_INVALID))
         std::cout << " FE_INVALID raised\n";
 }

Possible output:
 cos(pi/3) = 0.5
 cos(pi/2) = 6.12323e-17
 cos(-3*pi/4) = -0.707107
 cos(+0) = 1
 cos(-0) = 1
 cos(INFINITY) = -nan
     FE_INVALID raised

See also
   sin
   sinf computes sine (\({\small\sin{x} }\)sin(x))
   sinl (function)
   (C++11)
   (C++11)
   tan
   tanf computes tangent (\({\small\tan{x} }\)tan(x))
   tanl (function)
   (C++11)
   (C++11)
   acos
   acosf computes arc cosine (\({\small\arccos{x} }\)arccos(x))
   acosl (function)
   (C++11)
   (C++11)
   cos(std::complex) computes cosine of a complex number (\({\small\cos{z} }\)cos(z))
                      (function template)
   cos(std::valarray) applies the function std::cos to each element of valarray
                      (function template)