std::asin

 

C++

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Technical Specifications

 

Numerics library

Common mathematical functions

Floating-point environment

Complex numbers

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Pseudo-random number generation

Compile-time rational arithmetic (C++11)

Generic numeric operations

iota (C++11)

accumulate

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adjacent_difference

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Common mathematical functions

Functions
Basic operations
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/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)
Macro constants
HUGE_VALFHUGE_VALHUGE_VALL (C++11)(C++11) INFINITY (C++11) NAN (C++11) math_errhandlingMATH_ERRNOMATH_ERREXCEPT (C++11)	FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C++11)(C++11)(C++11)(C++11)(C++11)

 

Defined in header <cmath>
float       asin( float arg );	(1)
double      asin( double arg );	(2)
long double asin( long double arg );	(3)
double      asin( Integral arg );	(4)	(since C++11)

Computes the principal value of the arc sine of arg.

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 of a floating-point or Integral type

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 <cmath>
#include <iostream>
#include <cerrno>
#include <cfenv>
#include <cstring>
 
#pragma STDC FENV_ACCESS ON
int main()
{
    std::cout << "asin(1.0) = " << asin(1) << '\n'
              << "2*asin(1.0) = " << 2*asin(1) << '\n'
              << "asin(-0.5) = " << asin(-0.5) << '\n'
              << "6*asin(-0.5) =" << 6*asin(-0.5) << '\n';
    // special values
    std::cout << "asin(0.0) = " << asin(0) << " asin(-0.0)=" << asin(-0.0) << '\n';
    // error handling 
    errno = 0; std::feclearexcept(FE_ALL_EXCEPT);
    std::cout << "asin(1.1) = " << asin(1.1) << '\n';
    if(errno == EDOM)
        std::cout << "    errno == EDOM: " << std::strerror(errno) << '\n';
    if(std::fetestexcept(FE_INVALID))
        std::cout << "    FE_INVALID raised" << '\n';
}

Possible output:

asin(1.0) = 1.5708
2*asin(1.0) = 3.14159
asin(-0.5) = -0.523599
6*asin(-0.5) = -3.14159
asin(0.0) = 0 asin(-0.0)=-0
asin(1.1) = nan
    errno == EDOM: Numerical argument out of domain
    FE_INVALID raised

See also

acos	computes arc cosine (arccos(x)) (function)
atan	computes arc tangent (arctan(x)) (function)
atan2	arc tangent, using signs to determine quadrants (function)
sin	computes sine (sin(x)) (function)
asin(std::complex) (C++11)	computes arc sine of a complex number (arcsin(z)) (function template)
asin(std::valarray)	applies the function std::asin to each element of valarray (function template)
C documentation for asin