NAME¶

std::tan,std::tanf,std::tanl - std::tan,std::tanf,std::tanl

Synopsis¶

Defined in header <cmath>
float tan ( float arg );
float tanf( float arg ); (since C++11)
double tan ( double arg ); (1) (2)
long double tan ( long double arg );
long double tanl( long double arg ); (3) (since C++11)
double tan ( IntegralType arg ); (4) (since C++11)

1-3) Computes the tangent 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 tangent of arg (tan(arg)) 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, it is returned unmodified
* 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
(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.

Example¶

// Run this code

#include <iostream>
#include <cmath>
#include <cerrno>
#include <cfenv>
// #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

See also¶

sin
sinf computes sine (\({\small\sin{x} }\)sin(x))
sinl (function)
(C++11)
(C++11)
cos
cosf computes cosine (\({\small\cos{x} }\)cos(x))
cosl (function)
(C++11)
(C++11)
atan
atanf computes arc tangent (\({\small\arctan{x} }\)arctan(x))
atanl (function)
(C++11)
(C++11)
tan(std::complex) computes tangent of a complex number (\({\small\tan{z} }\)tan(z))
(function template)
tan(std::valarray) applies the function std::tan to each element of valarray
(function template)