std::asin, std::asinf, std::asinl - cppreference.com (original) (raw)
| Defined in header | ||
|---|---|---|
| (1) | ||
| float asin ( float num ); double asin ( double num ); long double asin ( long double num ); | (until C++23) | |
| /*floating-point-type*/ asin ( /*floating-point-type*/ num ); | (since C++23) (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 | ||
| template< /*math-floating-point*/ V > constexpr /*deduced-simd-t*/<V> asin ( const V& v_num ); | (S) | (since C++26) |
| Additional overloads (since C++11) | ||
| Defined in header | ||
| template< class Integer > double asin ( Integer num ); | (A) | (constexpr since C++26) |
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)
| 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 [- , +], 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
#include #include #include #include #include // #pragma STDC FENV_ACCESS ON int main() { std::cout << "asin(1.0) = " << asin(1) << '\n' << "2asin(1.0) = " << 2 * asin(1) << '\n' << "asin(-0.5) = " << asin(-0.5) << '\n' << "6asin(-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 2asin(1.0) = 3.14159 asin(-0.5) = -0.523599 6asin(-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
| acosacosfacosl(C++11)(C++11) | computes arc cosine (\({\small\arccos{x}}\)arccos(x)) (function) [edit] |
|---|---|
| atanatanfatanl(C++11)(C++11) | computes arc tangent (\({\small\arctan{x}}\)arctan(x)) (function) [edit] |
| atan2atan2fatan2l(C++11)(C++11) | arc tangent, using signs to determine quadrants (function) [edit] |
| sinsinfsinl(C++11)(C++11) | computes sine (\({\small\sin{x}}\)sin(x)) (function) [edit] |
| asin(std::complex)(C++11) | computes arc sine of a complex number (\({\small\arcsin{z}}\)arcsin(z)) (function template) [edit] |
| asin(std::valarray) | applies the function std::asin to each element of valarray (function template) [edit] |
| C documentation for asin |