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