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

abs(int)labsllabsimaxabs (C++11)
abs(float)fabs
divldivlldivimaxdiv (C++11)

fmod
remainder (C++11)
remquo (C++11)
fma (C++11)
fmax (C++11)
fmin (C++11)
fdim (C++11)
nannanfnanl (C++11)(C++11)(C++11)

Exponential functions

exp
exp2 (C++11)
expm1 (C++11)

log
log10
log1p (C++11)
log2 (C++11)

Power functions

sqrt
cbrt (C++11)

hypot (C++11)
pow

Trigonometric and
hyperbolic functions

sin
cos
tan
asin
acos
atan
atan2

sinh
cosh
tanh
asinh (C++11)
acosh (C++11)
atanh (C++11)

Error and gamma functions

erf (C++11)
erfc (C++11)

lgamma (C++11)
tgamma (C++11)

Nearest integer floating point operations

ceil
floor
roundlroundllround (C++11)(C++11)(C++11)

trunc (C++11)
nearbyint (C++11)
rintlrintllrint (C++11)(C++11)(C++11)

Floating point manipulation functions

ldexp
scalbnscalbln (C++11)(C++11)
ilogb (C++11)
logb (C++11)

frexp
modf
nextafternexttoward (C++11)(C++11)
copysign (C++11)

Classification and comparison

fpclassify (C++11)
isfinite (C++11)
isinf (C++11)
isnan (C++11)
isnormal (C++11)
signbit (C++11)

isgreater (C++11)
isgreaterequal (C++11)
isless (C++11)
islessequal (C++11)
islessgreater (C++11)
isunordered (C++11)

Types

div_t
ldiv_t
lldiv_t (C++11)

imaxdiv_t (C++11)
float_t (C++11)
double_t (C++11)

Macro constants

HUGE_VALFHUGE_VALHUGE_VALL (C++11)(C++11)
math_errhandlingMATH_ERRNOMATH_ERREXCEPT (C++11)
INFINITY (C++11)
NAN (C++11)

Classification
FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C++11) (C++11) (C++11) (C++11) (C++11)

Defined in header `<cmath>`
	(1)
float tan ( float num ) ; double tan ( double num ); long double tan ( long double num ) ;			(until C++23)
/floating-point-type/ tan ( /floating-point-type/ num ) ;			(since C++23) (constexpr since C++26)
float tanf( float num );		(2)	(since C++11) (constexpr since C++26)
long double tanl( long double num ) ;		(3)	(since C++11) (constexpr since C++26)
SIMD overload (since C++26)
Defined in header `<simd>`
template < /math-floating-point/ V > constexpr /deduced-simd-t/<V> tan ( const V& v_num ) ;		(S)	(since C++26)
Additional overloads (since C++11)
Defined in header `<cmath>`
template < class Integer > double tan ( Integer num ) ;		(A)	(constexpr since C++26)

1-3) Computes the tangent of num (measured in radians). The library provides overloads of std::tan for all cv-unqualified floating-point types as the type of the parameter. (since C++23)

S) The SIMD overload performs an element-wise std::tan on v_num.

(See math-floating-point and deduced-simd-t

(since C++26)

A) Additional overloads are provided for all integer types, which are treated as double.

(since C++11)

Parameters

num

-

floating-point or integer value representing angle in radians

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.

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 $π(1/2 + n)$

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) )

Example

Run this code

#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

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Diagnostics library
Memory management library
Metaprogramming library (C++11)
General utilities library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Strings library
Text processing library
Numerics library
Date and time library
Input/output library
Filesystem library (C++17)
Concurrency support library (C++11)
Execution support library (C++26)
Technical specifications
Symbols index
External libraries

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)
C documentation for tan