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Defined in header <cmath> | ||
| (1) | ||
float sqrt(float num); double sqrt(double num); | (until C++23) | |
/*floating-point-type*/ sqrt(/*floating-point-type*/ num); | (since C++23) (constexpr since C++26) | |
float sqrtf(float num); | (2) | (since C++11) (constexpr since C++26) |
longdouble sqrtl(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 sqrt( Integer num); | (A) | (constexpr since C++26) |
std::sqrt 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::sqrt 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, square root ofnum (\({\small \sqrt{num} }\)√num), 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 less than zero.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
std::sqrt is required by the IEEE standard to be correctly rounded from the infinitely precise result. In particular, the exact result is produced if it can be represented in the floating-point type. The only other operations which require this are thearithmetic operators and the functionstd::fma. Other functions, includingstd::pow, are not so constrained.
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::sqrt(num) has the same effect asstd::sqrt(static_cast<double>(num)).
#include <cerrno>#include <cfenv>#include <cmath>#include <cstring>#include <iostream>// #pragma STDC FENV_ACCESS ON int main(){// normal usestd::cout<<"sqrt(100) = "<< std::sqrt(100)<<'\n'<<"sqrt(2) = "<< std::sqrt(2)<<'\n'<<"golden ratio = "<<(1+ std::sqrt(5))/2<<'\n'; // special valuesstd::cout<<"sqrt(-0) = "<< std::sqrt(-0.0)<<'\n'; // error handlingerrno=0;std::feclearexcept(FE_ALL_EXCEPT); std::cout<<"sqrt(-1.0) = "<< std::sqrt(-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:
sqrt(100) = 10sqrt(2) = 1.41421golden ratio = 1.61803sqrt(-0) = -0sqrt(-1.0) = -nan errno = EDOM Numerical argument out of domain FE_INVALID raised
(C++11)(C++11) | raises a number to the given power (\(\small{x^y}\)xy) (function)[edit] |
(C++11)(C++11)(C++11) | computes cube root (\(\small{\sqrt[3]{x}}\)3√x) (function)[edit] |
(C++11)(C++11)(C++11) | computes hypotenuse\(\scriptsize{\sqrt{x^2+y^2}}\)√x2 +y2 and\(\scriptsize{\sqrt{x^2+y^2+z^2}}\)√x2 +y2 +z2 (since C++17) (function)[edit] |
| complex square root in the range of the right half-plane (function template)[edit] | |
| applies the functionstd::sqrt to each element of valarray (function template)[edit] | |
C documentation forsqrt | |
