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| Nearest integer floating point operations | |||||||||||||||||||||||||||||||||||||||||
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Defined in header <cmath> | ||
| (1) | ||
float acos(float num); double acos(double num); | (until C++23) | |
/*floating-point-type*/ acos(/*floating-point-type*/ num); | (since C++23) (constexpr since C++26) | |
float acosf(float num); | (2) | (since C++11) (constexpr since C++26) |
longdouble acosl(longdouble num); | (3) | (since C++11) (constexpr since C++26) |
SIMD overload(since C++26) | ||
Defined in header <simd> | ||
template</*math-floating-point*/ V> constexpr/*deduced-simd-t*/<V> | (S) | (since C++26) |
Additional overloads(since C++11) | ||
Defined in header <cmath> | ||
template<class Integer> double acos( Integer num); | (A) | (constexpr since C++26) |
std::acos 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::acos onv_num.
| (since C++26) |
A) Additional overloads are provided for all integer types, which are treated asdouble. | (since C++11) |
Contents |
| num | - | floating-point or integer value |
If no errors occur, the arc cosine ofnum (arccos(num)) in the range[0, π], 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.
Errors are reported as specified inmath_errhandling.
Domain error occurs ifnum is outside the range[-1.0, 1.0].
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
+0 is returned.The additional overloads are not required to be provided exactly as(A). They only need to be sufficient to ensure that for their argumentnum of integer type,std::acos(num) has the same effect asstd::acos(static_cast<double>(num)).
#include <cerrno>#include <cfenv>#include <cmath>#include <cstring>#include <iostream> // #pragma STDC FENV_ACCESS ON int main(){std::cout<<"acos(-1) = "<< std::acos(-1)<<'\n'<<"acos(0.0) = "<< std::acos(0.0)<<'\n'<<"2*acos(0.0) = "<<2* std::acos(0)<<'\n'<<"acos(0.5) = "<< std::acos(0.5)<<'\n'<<"3*acos(0.5) = "<<3* std::acos(0.5)<<'\n'<<"acos(1) = "<< std::acos(1)<<'\n'; // error handlingerrno=0;std::feclearexcept(FE_ALL_EXCEPT); std::cout<<"acos(1.1) = "<< std::acos(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';}
Output:
acos(-1) = 3.14159acos(0.0) = 1.57082*acos(0.0) = 3.14159acos(0.5) = 1.04723*acos(0.5) = 3.14159acos(1) = 0acos(1.1) = nan errno == EDOM: Numerical argument out of domain FE_INVALID raised
(C++11)(C++11) | computes arc sine (\({\small\arcsin{x}}\)arcsin(x)) (function)[edit] |
(C++11)(C++11) | computes arc tangent (\({\small\arctan{x}}\)arctan(x)) (function)[edit] |
(C++11)(C++11) | arc tangent, using signs to determine quadrants (function)[edit] |
(C++11)(C++11) | computes cosine (\({\small\cos{x}}\)cos(x)) (function)[edit] |
(C++11) | computes arc cosine of a complex number (\({\small\arccos{z}}\)arccos(z)) (function template)[edit] |
| applies the functionstd::acos to each element of valarray (function template)[edit] | |
C documentation foracos | |
