Defined in header <cmath> | ||
---|---|---|
float cos( float arg ); | (1) | |
double cos( double arg ); | (2) | |
long double cos( long double arg ); | (3) | |
double cos( Integral arg ); | (4) | (since C++11) |
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 | (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
#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
computes sine (sin(x)) (function) | |
computes tangent (tan(x)) (function) | |
computes arc cosine (arccos(x)) (function) | |
computes cosine of a complex number (cos(z)) (function template) | |
applies the function std::cos to each element of valarray (function template) | |
C documentation for cos |
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