NAME

std::asin,std::asinf,std::asinl - std::asin,std::asinf,std::asinl

Synopsis

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

1-3) 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
acosf computes arc cosine (\({\small\arccos{x} }\)arccos(x))
acosl (function)
(C++11)
(C++11)
atan
atanf computes arc tangent (\({\small\arctan{x} }\)arctan(x))
atanl (function)
(C++11)
(C++11)
atan2
atan2f arc tangent, using signs to determine quadrants
atan2l (function)
(C++11)
(C++11)
sin
sinf computes sine (\({\small\sin{x} }\)sin(x))
sinl (function)
(C++11)
(C++11)
asin(std::complex) computes arc sine of a complex number (\({\small\arcsin{z}
(C++11) }\)arcsin(z))
(function template)
asin(std::valarray) applies the function std::asin to each element of valarray
(function template)