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

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

Compiler support
Freestanding and hosted
Language
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Technical specifications
Symbols index
External libraries

Common mathematical functions
Mathematical special functions (C++17)
Mathematical constants (C++20)
Floating-point environment (C++11)
Complex numbers
Numeric arrays
Pseudo-random number generation
Factor operations
gcd (C++17)
lcm (C++17)
Interpolations
midpoint (C++20)
lerp (C++20)
Generic numeric operations
iota (C++11)
ranges::iota (C++23)
accumulate
inner_product
adjacent_difference
partial_sum
reduce (C++17)
transform_reduce (C++17)
inclusive_scan (C++17)
exclusive_scan (C++17)
transform_inclusive_scan (C++17)
transform_exclusive_scan (C++17)
Bit operations
bit_cast (C++20)
byteswap (C++23)
has_single_bit (C++20)
bit_ceil (C++20)
bit_floor (C++20)
bit_width (C++20)
rotl (C++20)
rotr (C++20)
countl_zero (C++20)
countl_one (C++20)
countr_zero (C++20)
countr_one (C++20)
popcount (C++20)
endian (C++20)

sinsinfsinl (C++11)(C++11)	computes sine (\({\small\sin{x} }\) $sin(x)$ ) (function)
coscosfcosl (C++11)(C++11)	computes cosine (\({\small\cos{x} }\) $cos(x)$ ) (function)
atanatanfatanl (C++11)(C++11)	computes arc tangent (\({\small\arctan{x} }\) $arctan(x)$ ) (function)
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)