Std::cos,std::cosf,std::cosl (3) Linux Manual Page

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 is large (until C++11)
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

std::cos,std::cosf,std::cosl (3) Linux Manual Page