std::tan, std::tanf, std::tanl
<cmath>
double tan ( double num );
tan ( /*floating-point-type*/ num );
(constexpr since C++26)
(constexpr since C++26)
(constexpr since C++26)
<simd>
constexpr /*deduced-simd-t*/<V>
<cmath>
double tan ( Integer num );
std::tan for all cv-unqualified floating-point types as the type of the parameter.(since C++23)std::tan on v_num.- (See math-floating-point and deduced-simd-t for their definitions.)
[edit] Parameters
[edit] Return value
If no errors occur, the tangent of num (tan(num)) is returned.
The result may have little or no significance if the magnitude of num 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.
[edit] 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, it is returned unmodified.
- if the argument is ±∞, NaN is returned and FE_INVALID is raised.
- if the argument is NaN, NaN is returned.
[edit] Notes
The case where the argument is infinite is not specified to be a domain error in C (to which C++ defers), but it is defined as a domain error in POSIX.
The function has mathematical poles at π(1/2 + n); however no common floating-point representation is able to represent π/2 exactly, thus there is no value of the argument for which a pole error occurs.
The additional overloads are not required to be provided exactly as (A). They only need to be sufficient to ensure that for their argument num of integer type, std::tan(num) has the same effect as std::tan(static_cast<double>(num)).
[edit] Example
#include <cerrno> #include <cfenv> #include <cmath> #include <iostream> // #pragma STDC FENV_ACCESS ON const double pi = std::acos (-1); // or C++20's std::numbers::pi int main() { // typical usage std::cout << "tan(1*pi/4) = " << std::tan(1*pi/4) << '\n' // 45° << "tan(3*pi/4) = " << std::tan(3*pi/4) << '\n' // 135° << "tan(5*pi/4) = " << std::tan(5*pi/4) << '\n' // -135° << "tan(7*pi/4) = " << std::tan(7*pi/4) << '\n'; // -45° // special values std::cout << "tan(+0) = " << std::tan(0.0) << '\n' << "tan(-0) = " << std::tan(-0.0) << '\n'; // error handling std::feclearexcept (FE_ALL_EXCEPT ); std::cout << "tan(INFINITY) = " << std::tan(INFINITY ) << '\n'; if (std::fetestexcept (FE_INVALID )) std::cout << " FE_INVALID raised\n"; }
Possible output:
tan(1*pi/4) = 1 tan(3*pi/4) = -1 tan(5*pi/4) = 1 tan(7*pi/4) = -1 tan(+0) = 0 tan(-0) = -0 tan(INFINITY) = -nan FE_INVALID raised