asin, asinf, asinl

 

C

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Headers

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Program utilities

Variadic function support

Error handling

Dynamic memory management

Strings library

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Numerics

Date and time utilities

Input/output support

Localization support

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       asinf(float arg );	(1)	(since C99)
double      asin(double arg );	(2)
longdouble asinl(longdouble arg );	(3)	(since C99)
_Decimal32  asind32( _Decimal32 arg );	(4)	(since C23)
_Decimal64  asind64( _Decimal64 arg );	(5)	(since C23)
_Decimal128 asind128( _Decimal128 arg );	(6)	(since C23)
Defined in header <tgmath.h>
#define asin( arg )	(7)	(since C99)

1-6) Computes the principal values of the arc sine of arg.

7) Type-generic macro: If the argument has type longdouble, (3) (asinl) is called. Otherwise, if the argument has integer type or the type double, (2) (asin) is called. Otherwise, (1) (asinf) is called. If the argument is complex, then the macro invokes the corresponding complex function (casinf, casin, casinl).

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

Return value

If no errors occur, the arc sine of arg (arcsin(arg)) in the range [-

π

2

 ; +

π

2

], is returned.

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.

Domain error occurs if arg is outside the range [-1.0; 1.0].

If the implementation supports IEEE floating-point arithmetic (IEC 60559):

• if the argument is ±0, it is returned unmodified;
• if |arg| > 1, a domain error occurs and NaN is returned;
• if the argument is NaN, NaN is returned.

Example

Run this code

#include <errno.h>#include <fenv.h>#include <math.h>#include <stdio.h>#include <string.h>   #ifndef __GNUC__#pragma STDC FENV_ACCESS ON#endif   int main(void){printf("asin( 1.0) = %+f, 2*asin( 1.0)=%+f\n", asin(1), 2* asin(1));printf("asin(-0.5) = %+f, 6*asin(-0.5)=%+f\n", asin(-0.5), 6* asin(-0.5));   // special valuesprintf("asin(0.0) = %1f, asin(-0.0)=%f\n", asin(+0.0), asin(-0.0));   // error handlingerrno=0;feclearexcept(FE_ALL_EXCEPT);printf("asin(1.1) = %f\n", asin(1.1));if(errno==EDOM)perror(" errno == EDOM");if(fetestexcept(FE_INVALID))puts(" FE_INVALID raised");}

Possible output:

asin( 1.0) = +1.570796, 2*asin( 1.0)=+3.141593 asin(-0.5) = -0.523599, 6*asin(-0.5)=-3.141593 asin(0.0) = 0.000000, asin(-0.0)=-0.000000 asin(1.1) = nan errno == EDOM: Numerical argument out of domain FE_INVALID raised

References

• C23 standard (ISO/IEC 9899:2024):

• 7.12.4.2 The asin functions (p: TBD)

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

• F.10.1.2 The asin functions (p: TBD)

• C17 standard (ISO/IEC 9899:2018):

• 7.12.4.2 The asin functions (p: 174)

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

• F.10.1.2 The asin functions (p: 378)

• C11 standard (ISO/IEC 9899:2011):

• 7.12.4.2 The asin functions (p: 238)

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

• F.10.1.2 The asin functions (p: 518)

• C99 standard (ISO/IEC 9899:1999):

• 7.12.4.2 The asin functions (p: 219)

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

• F.9.1.2 The asin functions (p: 456)

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

• 4.5.2.2 The asin function

See also

acosacosfacosl (C99)(C99)	computes arc cosine (\({\small\arccos{x} }\)arccos(x)) (function)
atanatanfatanl (C99)(C99)	computes arc tangent (\({\small\arctan{x} }\)arctan(x)) (function)
atan2atan2fatan2l (C99)(C99)	computes arc tangent, using signs to determine quadrants (function)
sinsinfsinl (C99)(C99)	computes sine (\({\small\sin{x} }\)sin(x)) (function)
casincasinfcasinl (C99)(C99)(C99)	computes the complex arc sine (function)
C++ documentation for asin