std::asin, std::asinf, std::asinl
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Defined in header
<cmath>
(1)
float asin ( float num );
(until C++23)
double asin ( double num );
/*floating-point-type*/
asin ( /*floating-point-type*/ num );
(since C++23) asin ( /*floating-point-type*/ num );
(constexpr since C++26)
float asinf( float num );
(2)
(since C++11) (constexpr since C++26)
long double asinl( 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 >
(S)
(since C++26)
constexpr /*deduced-simd-t*/<V>
Additional overloads (since C++11)
Defined in header
<cmath>
template< class Integer >
double asin ( Integer num );
(A)
(constexpr since C++26)
double asin ( Integer num );
1-3) Computes the principal value of the arc sine of num. The library provides overloads of
std::asin 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::asin on v_num.- (See math-floating-point and deduced-simd-t for their definitions.)
A) Additional overloads are provided for all integer types, which are treated as double.
(since C++11)[edit] Parameters
num
-
floating-point or integer value
[edit] Return value
If no errors occur, the arc sine of num (arcsin(num)) 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.
[edit] Error handling
Errors are reported as specified in math_errhandling .
Domain error occurs if num 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 |num| > 1, a domain error occurs and NaN is returned.
- if the argument is NaN, NaN is returned.
[edit] Notes
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::asin(num) has the same effect as std::asin(static_cast<double>(num)).
[edit] Example
Run this code
#include <cerrno> #include <cfenv> #include <cmath> #include <cstring> #include <iostream> // #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
[edit] See also
(C++11)
(function template) [edit]
C documentation for asin