tan, tanf, tanl

 

C

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Concurrency support(C11)

Technical Specifications

Symbol index

 

Numerics

Common mathematical functions

Floating-point environment(C99)

Pseudo-random number generation

Complex number arithmetic(C99)

Type-generic math(C99)

Bit manipulation(C23)

Checked integer arithmetic(C23)

 

Common mathematical functions

Functions Basic operations abslabsllabsimaxabs (C99)(C99) fabs divldivlldivimaxdiv (C99)(C99) fmod remainder (C99) remquo (C99) fma (C99) fdim (C99) nannanfnanlnandN (C99)(C99)(C99)(C23) Maximum/minimum operations fmax (C99) fmin (C99) fmaximum (C23) fminimum (C23) fmaximum_mag (C23)  fmaximum_num (C23) fminimum_mag (C23) fminimum_num (C23) fmaximum_mag_num (C23) fminimum_mag_num (C23)   Exponential functions exp exp10 (C23) exp2 (C99) expm1 (C99) exp10m1 (C23) exp2m1 (C23) log log10 log2 (C99) log1plogp1 (C99)(C23) log10p1 (C23) log2p1 (C23) Power functions sqrt cbrt (C99) rootn (C23) rsqrt (C23) hypot (C99) compound (C23) pow pown (C23) powr (C23) Trigonometric and hyperbolic functions sin cos tan asin acos atan atan2 sinpi (C23) cospi (C23) tanpi (C23) asinpi (C23) acospi (C23) atanpi (C23) atan2pi (C23) sinh cosh tanh asinh (C99) acosh (C99) atanh (C99)

Nearest integer floating-point ceil floor roundlroundllround (C99)(C99)(C99) roundeven (C23) trunc (C99) nearbyint (C99) rintlrintllrint (C99)(C99)(C99) fromfpfromfpxufromfpufromfpx (C23)(C23)(C23)(C23) Floating-point manipulation ldexp frexp scalbnscalbln (C99)(C99) ilogbllogb (C99)(C23) logb (C99) modf nextafternexttoward (C99)(C99) nextupnextdown (C23)(C23) copysign (C99) canonicalize (C23) Narrowing operations fadd (C23) fsub (C23) fmul (C23) fdiv (C23) ffma (C23) fsqrt (C23) Quantum and quantum exponent quantizedN (C23) quantumdN (C23) samequantumdN (C23) llquantexpdN (C23) Decimal re-encoding functions encodedecdN (C23) decodedecdN (C23) encodebindN (C23) decodebindN (C23) Total order and payload functions totalorder (C23) getpayload (C23) setpayload (C23) setpayloadsig (C23) Classification fpclassify (C99) iscanonical (C23)  isfinite (C99) isinf (C99) isnan (C99) isnormal (C99) signbit (C99) issubnormal (C23) iszero (C23) isgreater (C99) isgreaterequal (C99)   isless (C99) islessequal (C99) islessgreater (C99) isunordered (C99) issignaling (C23) iseqsig (C23)

Error and gamma functions erf (C99) erfc (C99) lgamma (C99) tgamma (C99) Types div_tldiv_tlldiv_timaxdiv_t (C99)(C99) float_tdouble_t (C99)(C99) _Decimal32_t_Decimal64_t (C23)(C23) Macro constants Special floating-point values HUGE_VALHUGE_VALFHUGE_VALLHUGE_VALDN (C99)(C99)(C23) INFINITYDEC_INFINITY (C99)(C23) NANDEC_NAN (C99)(C23) Arguments and return values FP_ILOGB0FP_ILOGBNAN (C99)(C99) FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C99)(C99)(C99)(C99)(C99) FP_LLOGB0FP_LLOGBNAN (C23)(C23) FP_INT_UPWARDFP_INT_DOWNWARDFP_INT_TOWARDZEROFP_INT_TONEARESTFROMZEROFP_INT_TONEAREST (C23)(C23)(C23)(C23)(C23) Error handling MATH_ERRNOMATH_ERRNOEXCEPT (C99)(C99)  math_errhandling (C99) Fast operation indicators FP_FAST_FMAFFP_FAST_FMA (C99)(C99) FP_FAST_FADDFP_FAST_FADDLFP_FAST_DADDLFP_FAST_DMADDDN (C23)(C23)(C23)(C23) FP_FAST_FMULFP_FAST_FMULLFP_FAST_DMULLFP_FAST_DMMULDN (C23)(C23)(C23)(C23) FP_FAST_FFMAFP_FAST_FFMALFP_FAST_DFMALFP_FAST_DMFMADN (C23)(C23)(C23)(C23) FP_FAST_FMALFP_FAST_FMADN (C99)(C23) FP_FAST_FSUBFP_FAST_FSUBLFP_FAST_DSUBLFP_FAST_DMSUBDN (C23)(C23)(C23)(C23) FP_FAST_FDIVFP_FAST_FDIVLFP_FAST_DDIVLFP_FAST_DMDIVDN (C23)(C23)(C23)(C23) FP_FAST_FSQRTFP_FAST_FSQRTLFP_FAST_DSQRTLFP_FAST_DMSQRTDN (C23)(C23)(C23)(C23)

 

Defined in header <math.h>
float       tanf(float arg );	(1)	(since C99)
double      tan(double arg );	(2)
longdouble tanl(longdouble arg );	(3)	(since C99)
_Decimal32  tand32( _Decimal32 arg );	(4)	(since C23)
_Decimal64  tand64( _Decimal64 arg );	(5)	(since C23)
_Decimal128 tand128( _Decimal128 arg );	(6)	(since C23)
Defined in header <tgmath.h>
#define tan( arg )	(7)	(since C99)

1-6) Computes the tangent of arg (measured in radians).

7) Type-generic macro: If the argument has type longdouble, (3) (tanl) is called. Otherwise, if the argument has integer type or the type double, (2) (tan) is called. Otherwise, (1) (tanf) is called. If the argument is complex, then the macro invokes the corresponding complex function (ctanf, ctan, ctanl).

The functions (4-6) are declared if and only if the implementation predefines __STDC_IEC_60559_DFP__ (i.e. the implementation supports decimal floating-point numbers).

(since C23)

Parameters

arg

-

floating-point value representing angle in radians

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 C99)

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, 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 <errno.h>#include <fenv.h>#include <math.h>#include <stdio.h>   #ifndef __GNUC__#pragma STDC FENV_ACCESS ON#endif   int main(void){constdouble pi =acos(-1);   // typical usageprintf("tan(pi*1/4) = %+f\n", tan(pi *1/4));// 45 degprintf("tan(pi*3/4) = %+f\n", tan(pi *3/4));// 135 degprintf("tan(pi*5/4) = %+f\n", tan(pi *5/4));// -135 degprintf("tan(pi*7/4) = %+f\n", tan(pi *7/4));// -45 deg   // special valuesprintf("tan(+0) = %f\n", tan(0.0));printf("tan(-0) = %f\n", tan(-0.0));   // error handlingfeclearexcept(FE_ALL_EXCEPT);printf("tan(INFINITY) = %f\n", tan(INFINITY));if(fetestexcept(FE_INVALID))puts(" FE_INVALID raised");}

Possible output:

tan(pi*1/4) = +1.000000 tan(pi*3/4) = -1.000000 tan(pi*5/4) = +1.000000 tan(pi*7/4) = -1.000000 tan(+0) = 0.000000 tan(-0) = -0.000000 tan(INFINITY) = -nan FE_INVALID raised

References

• C23 standard (ISO/IEC 9899:2024):

• 7.12.4.7 The tan functions (p: TBD)

• 7.25 Type-generic math <tgmath.h> (p: TBD)

• F.10.1.7 The tan functions (p: TBD)

• C17 standard (ISO/IEC 9899:2018):

• 7.12.4.7 The tan functions (p: 175)

• 7.25 Type-generic math <tgmath.h> (p: 272-273)

• F.10.1.7 The tan functions (p: 378)

• C11 standard (ISO/IEC 9899:2011):

• 7.12.4.7 The tan functions (p: 240)

• 7.25 Type-generic math <tgmath.h> (p: 373-375)

• F.10.1.7 The tan functions (p: 519)

• C99 standard (ISO/IEC 9899:1999):

• 7.12.4.7 The tan functions (p: 220)

• 7.22 Type-generic math <tgmath.h> (p: 335-337)

• F.9.1.7 The tan functions (p: 457)

• C89/C90 standard (ISO/IEC 9899:1990):

• 4.5.2.7 The tan function

See also

sinsinfsinl (C99)(C99)	computes sine (\({\small\sin{x} }\)sin(x)) (function)
coscosfcosl (C99)(C99)	computes cosine (\({\small\cos{x} }\)cos(x)) (function)
atanatanfatanl (C99)(C99)	computes arc tangent (\({\small\arctan{x} }\)arctan(x)) (function)
ctanctanfctanl (C99)(C99)(C99)	computes the complex tangent (function)
C++ documentation for tan